Merge 8.7

98 files changed, 9965 insertions, 4484 deletions

diff --git a/.github/workflows/linux-build.yml b/.github/workflows/linux-build.yml
index 8562bb5..7ba9e89 100644
--- a/.github/workflows/linux-build.yml
+++ b/.github/workflows/linux-build.yml
@@ -4,7 +4,7 @@ permissions:
   contents: read
 jobs:
   gcc:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     strategy:
       matrix:
         cfgopt:
diff --git a/.github/workflows/onefiledist.yml b/.github/workflows/onefiledist.yml
index c4212d4..45ce720 100644
--- a/.github/workflows/onefiledist.yml
+++ b/.github/workflows/onefiledist.yml
@@ -5,7 +5,7 @@ permissions:
 jobs:
   linux:
     name: Linux
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     defaults:
       run:
         shell: bash
diff --git a/.gitignore b/.gitignore
index 74bf502..504f1e4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -26,7 +26,7 @@ manifest.uuid
 _FOSSIL_
 */tclConfig.sh
 */tclsh*
-*/tcltest*
+*/tcltest
 */versions.vc
 */version.vc
 */libtcl.vfs
diff --git a/doc/CrtObjCmd.3 b/doc/CrtObjCmd.3
index 8d10418..0490bd7 100644
--- a/doc/CrtObjCmd.3
+++ b/doc/CrtObjCmd.3
@@ -8,7 +8,7 @@
 .so man.macros
 .BS
 .SH NAME
-Tcl_CreateObjCommand, Tcl_DeleteCommand, Tcl_DeleteCommandFromToken, Tcl_GetCommandInfo, Tcl_GetCommandInfoFromToken, Tcl_SetCommandInfo, Tcl_SetCommandInfoFromToken, Tcl_GetCommandName, Tcl_GetCommandFullName, Tcl_GetCommandFromObj \- implement new commands in C
+Tcl_CreateObjCommand, Tcl_CreateObjCommand2, Tcl_DeleteCommand, Tcl_DeleteCommandFromToken, Tcl_GetCommandInfo, Tcl_GetCommandInfoFromToken, Tcl_SetCommandInfo, Tcl_SetCommandInfoFromToken, Tcl_GetCommandName, Tcl_GetCommandFullName, Tcl_GetCommandFromObj \- implement new commands in C
 .SH SYNOPSIS
 .nf
 \fB#include <tcl.h>\fR
@@ -16,6 +16,9 @@ Tcl_CreateObjCommand, Tcl_DeleteCommand, Tcl_DeleteCommandFromToken, Tcl_GetComm
 Tcl_Command
 \fBTcl_CreateObjCommand\fR(\fIinterp, cmdName, proc, clientData, deleteProc\fR)
 .sp
+Tcl_Command
+\fBTcl_CreateObjCommand2\fR(\fIinterp, cmdName, proc2, clientData, deleteProc\fR)
+.sp
 int
 \fBTcl_DeleteCommand\fR(\fIinterp, cmdName\fR)
 .sp
@@ -52,6 +55,9 @@ Name of command.
 .AP Tcl_ObjCmdProc *proc in
 Implementation of the new command: \fIproc\fR will be called whenever
 \fIcmdName\fR is invoked as a command.
+.AP Tcl_ObjCmdProc2 *proc2 in
+Implementation of the new command: \fIproc2\fR will be called whenever
+\fIcmdName\fR is invoked as a command.
 .AP ClientData clientData in
 Arbitrary one-word value to pass to \fIproc\fR and \fIdeleteProc\fR.
 .AP Tcl_CmdDeleteProc *deleteProc in
@@ -174,6 +180,17 @@ typedef void \fBTcl_CmdDeleteProc\fR(
 The \fIclientData\fR argument will be the same as the \fIclientData\fR
 argument passed to \fBTcl_CreateObjCommand\fR.
 .PP
+\fBTcl_CreateObjCommand2\fR does the same as \fBTcl_CreateObjCommand\fR,
+except its \fIproc2\fR argument is of type \fBTcl_ObjCmdProc2\fR.
+.PP
+.CS
+typedef int \fBTcl_ObjCmdProc2\fR(
+        ClientData \fIclientData\fR,
+        Tcl_Interp *\fIinterp\fR,
+        size_t \fIobjc\fR,
+        Tcl_Obj *const \fIobjv\fR[]);
+.CE
+.PP
 \fBTcl_DeleteCommand\fR deletes a command from a command interpreter.
 Once the call completes, attempts to invoke \fIcmdName\fR in
 \fIinterp\fR will result in errors.
diff --git a/doc/CrtTrace.3 b/doc/CrtTrace.3
index 620c081..417c892 100644
--- a/doc/CrtTrace.3
+++ b/doc/CrtTrace.3
@@ -10,7 +10,7 @@
 .so man.macros
 .BS
 .SH NAME
-Tcl_CreateTrace, Tcl_CreateObjTrace, Tcl_DeleteTrace \- arrange for command execution to be traced
+Tcl_CreateTrace, Tcl_CreateObjTrace, Tcl_CreateObjTrace2, Tcl_DeleteTrace \- arrange for command execution to be traced
 .SH SYNOPSIS
 .nf
 \fB#include <tcl.h>\fR
@@ -21,6 +21,9 @@ Tcl_Trace
 Tcl_Trace
 \fBTcl_CreateObjTrace\fR(\fIinterp, level, flags, objProc, clientData, deleteProc\fR)
 .sp
+Tcl_Trace
+\fBTcl_CreateObjTrace2\fR(\fIinterp, level, flags, objProc2, clientData, deleteProc\fR)
+.sp
 \fBTcl_DeleteTrace\fR(\fIinterp, trace\fR)
 .SH ARGUMENTS
 .AS Tcl_CmdObjTraceDeleteProc *deleteProc
@@ -38,11 +41,14 @@ Flags governing the trace execution.  See below for details.
 .AP Tcl_CmdObjTraceProc *objProc in
 Procedure to call for each command that is executed.  See below for
 details of the calling sequence.
+.AP Tcl_CmdObjTraceProc2 *objProc2 in
+Procedure to call for each command that is executed.  See below for
+details of the calling sequence.
 .AP Tcl_CmdTraceProc *proc in
 Procedure to call for each command that is executed.  See below for
 details on the calling sequence.
 .AP ClientData clientData in
-Arbitrary one-word value to pass to \fIobjProc\fR or \fIproc\fR.
+Arbitrary one-word value to pass to \fIobjProc\fR, \fIobjProc2\fR or \fIproc\fR.
 .AP Tcl_CmdObjTraceDeleteProc *deleteProc in
 Procedure to call when the trace is deleted.  See below for details of
 the calling sequence.  A NULL pointer is permissible and results in no
diff --git a/doc/Eval.3 b/doc/Eval.3
index 5929a83..3ae0bce 100644
--- a/doc/Eval.3
+++ b/doc/Eval.3
@@ -54,7 +54,7 @@ ORed combination of flag bits that specify additional options.
 .AP "const char" *fileName in
 Name of a file containing a Tcl script.
 .AP int objc in
-The number of values in the array pointed to by \fIobjPtr\fR;
+The number of values in the array pointed to by \fIobjv\fR;
 this is also the number of words in the command.
 .AP Tcl_Obj **objv in
 Points to an array of pointers to values; each value holds the
diff --git a/doc/NRE.3 b/doc/NRE.3
index 72bb370..f76938a 100644
--- a/doc/NRE.3
+++ b/doc/NRE.3
@@ -9,7 +9,7 @@
 .so man.macros
 .BS
 .SH NAME
-Tcl_NRCreateCommand, Tcl_NRCallObjProc, Tcl_NREvalObj, Tcl_NREvalObjv, Tcl_NRCmdSwap, Tcl_NRExprObj, Tcl_NRAddCallback \- Non-Recursive (stackless) evaluation of Tcl scripts.
+Tcl_NRCreateCommand, Tcl_NRCreateCommand2, Tcl_NRCallObjProc, Tcl_NRCallObjProc2, Tcl_NREvalObj, Tcl_NREvalObjv, Tcl_NRCmdSwap, Tcl_NRExprObj, Tcl_NRAddCallback \- Non-Recursive (stackless) evaluation of Tcl scripts.
 .SH SYNOPSIS
 .nf
 \fB#include <tcl.h>\fR
@@ -18,10 +18,17 @@ Tcl_Command
 \fBTcl_NRCreateCommand\fR(\fIinterp, cmdName, proc, nreProc, clientData,
                     deleteProc\fR)
 .sp
+Tcl_Command
+\fBTcl_NRCreateCommand2\fR(\fIinterp, cmdName, proc2, nreProc2, clientData,
+                    deleteProc\fR)
+.sp
 int
 \fBTcl_NRCallObjProc\fR(\fIinterp, nreProc, clientData, objc, objv\fR)
 .sp
 int
+\fBTcl_NRCallObjProc2\fR(\fIinterp, nreProc2, clientData, objc, objv\fR)
+.sp
+int
 \fBTcl_NREvalObj\fR(\fIinterp, objPtr, flags\fR)
 .sp
 int
@@ -47,8 +54,15 @@ Called in order to evaluate a command.  Is often just a small wrapper that uses
 \fBTcl_NRCallObjProc\fR to call \fInreProc\fR using a new trampoline.  Behaves
 in the same way as the \fIproc\fR argument to \fBTcl_CreateObjCommand\fR(3)
 (\fIq.v.\fR).
+.AP Tcl_ObjCmdProc2 *proc2 in
+Called in order to evaluate a command.  Is often just a small wrapper that uses
+\fBTcl_NRCallObjProc2\fR to call \fInreProc2\fR using a new trampoline.  Behaves
+in the same way as the \fIproc2\fR argument to \fBTcl_CreateObjCommand2\fR(3)
+(\fIq.v.\fR).
 .AP Tcl_ObjCmdProc *nreProc in
 Called instead of \fIproc\fR when a trampoline is already in use.
+.AP Tcl_ObjCmdProc2 *nreProc2 in
+Called instead of \fIproc2\fR when a trampoline is already in use.
 .AP ClientData clientData in
 Arbitrary one-word value passed to \fIproc\fR, \fInreProc\fR, \fIdeleteProc\fR
 and \fIobjProc\fR.
@@ -104,6 +118,9 @@ first deleted.  If \fIinterp\fR is in the process of being deleted
 \fBTcl_NRCreateCommand\fR does not create any command, does not delete any
 command, and returns NULL.
 .PP
+\fBTcl_NRCreateCommand2\fR, is an alternative to \fBTcl_NRCreateCommand\fR
+in the same way as \fBTcl_CreateObjCommand2\fR.
+.PP
 \fBTcl_NREvalObj\fR pushes a function that is like \fBTcl_EvalObjEx\fR but
 consumes no space on the C stack.
 .PP
diff --git a/doc/TraceVar.3 b/doc/TraceVar.3
index 7751cf7..5de6a44 100644
--- a/doc/TraceVar.3
+++ b/doc/TraceVar.3
@@ -126,8 +126,8 @@ It should have arguments and result that match the type
 typedef char *\fBTcl_VarTraceProc\fR(
         ClientData \fIclientData\fR,
         Tcl_Interp *\fIinterp\fR,
-        char *\fIname1\fR,
-        char *\fIname2\fR,
+        const char *\fIname1\fR,
+        const char *\fIname2\fR,
         int \fIflags\fR);
 .CE
 .PP
diff --git a/doc/after.n b/doc/after.n
index 3d0d2c4..1a814e0 100644
--- a/doc/after.n
+++ b/doc/after.n
@@ -33,6 +33,7 @@ depending on the first argument to the command:
 \fBafter \fIms\fR
 .
 \fIMs\fR must be an integer giving a time in milliseconds.
+A negative number is treated as 0.
 The command sleeps for \fIms\fR milliseconds and then returns.
 While the command is sleeping the application does not respond to
 events.
@@ -52,6 +53,9 @@ the background error will be reported by the command
 registered with \fBinterp bgerror\fR.
 The \fBafter\fR command returns an identifier that can be used
 to cancel the delayed command using \fBafter cancel\fR.
+A \fIms\fR value of 0 (or negative) queues the event immediately with
+priority over other event types (if not installed withn an event proc,
+which will wait for next round of events).
 .TP
 \fBafter cancel \fIid\fR
 .
diff --git a/doc/http.n b/doc/http.n
index 4781a1b..d531995 100644
--- a/doc/http.n
+++ b/doc/http.n
@@ -173,6 +173,19 @@ retrying the POST.  The value \fBtrue\fR should be used only under certain
 conditions. See the \fBPERSISTENT SOCKETS\fR section for details. The
 default is 0.
 .TP
+\fB\-threadlevel\fR \fIlevel\fR
+.
+Specifies whether and how to use the \fBThread\fR package.  Possible values of \fIlevel\fR are 0, 1 or 2.
+.RS
+.PP
+.DS
+0 - (the default) do not use Thread
+1 - use Thread if it is available, do not use it if it is unavailable
+2 - use Thread if it is available, raise an error if it is unavailable
+.DE
+The Tcl \fBsocket -async\fR command can block in adverse cases (e.g. a slow DNS lookup).  Using the Thread package works around this problem, for both HTTP and HTTPS transactions.  Values of \fIlevel\fR other than 0 are available only to the main interpreter in each thread.  See section \fBTHREADS\fR for more information.
+.RE
+.TP
 \fB\-urlencoding\fR \fIencoding\fR
 .
 The \fIencoding\fR used for creating the x-url-encoded URLs with
@@ -986,6 +999,20 @@ the server response code is a 307 redirect, and the response header
 again in order to fetch this URL.
 See https://w3c.github.io/webappsec-upgrade-insecure-requests/
 .PP
+.SH THREADS
+.PP
+.SS "PURPOSE"
+.PP
+Command \fB::http::geturl\fR uses the Tcl \fB::socket\fR command with the \-async option to connect to a remote server, but the return from this command can be delayed in adverse cases (e.g. a slow DNS lookup), preventing the event loop from processing other events.  This delay is avoided if the \fB::socket\fR command is evaluated in another thread.  The Thread package is not part of Tcl but is provided in "Batteries Included" distributions.  Instead of the \fB::socket\fR command, the http package uses \fB::http::socket\fR which makes connections in the manner specified by the value of \-threadlevel and the availability of package Thread.
+.PP
+.SS "WITH TLS (HTTPS)"
+.PP
+The same \-threadlevel configuration applies to both HTTP and HTTPS connections. HTTPS is enabled by using the \fBhttp::register\fR command, typically by specifying the \fB::tls::socket\fR command of the tls package to handle TLS cryptography.  The \fB::tls::socket\fR command connects to the remote server by using the command specified by the value of variable \fB::tls::socketCmd\fR, and this value defaults to "::socket".  If http::geturl finds that \fB::tls::socketCmd\fR has this value, it replaces it with the value "::http::socket".  If \fB::tls::socketCmd\fR has a value other than "::socket", i.e. if the script or the Tcl installation has replaced the value "::socket" with the name of a different command, then http does not change the value.  The script or installation that modified \fB::tls::socketCmd\fR is responsible for integrating \fB::http::socket\fR into its own replacement command.
+.PP
+.SS "WITH A CHILD INTERPRETER"
+.PP
+The peer thread can transfer the socket only to the main interpreter of the script's thread.  Therefore the thread-based \fB::http::socket\fR works with non-zero \-threadlevel values only if the script runs in the main interpreter.  A child interpreter must use \-threadlevel 0 unless the parent interpreter has provided alternative facilities.  The main parent interpreter may grant full \-threadlevel facilities to a child interpreter, for example by aliasing, to \fB::http::socket\fR in the child, a command that runs \fBhttp::socket\fR in the parent, and then transfers the socket to the child.
+.PP
 .SH EXAMPLE
 .PP
 This example creates a procedure to copy a URL to a file while printing a
diff --git a/generic/tcl.decls b/generic/tcl.decls
index 99c0e25..d08ba0a 100644
--- a/generic/tcl.decls
+++ b/generic/tcl.decls
@@ -2502,6 +2502,27 @@ declare 673 {
     int TclGetUniChar(Tcl_Obj *objPtr, int index)
 }
 
+declare 676 {
+    Tcl_Command Tcl_CreateObjCommand2(Tcl_Interp *interp,
+	    const char *cmdName,
+	    Tcl_ObjCmdProc2 *proc2, void *clientData,
+	    Tcl_CmdDeleteProc *deleteProc)
+}
+declare 677 {
+    Tcl_Trace Tcl_CreateObjTrace2(Tcl_Interp *interp, int level, int flags,
+	    Tcl_CmdObjTraceProc2 *objProc2, void *clientData,
+	    Tcl_CmdObjTraceDeleteProc *delProc)
+}
+declare 678 {
+    Tcl_Command Tcl_NRCreateCommand2(Tcl_Interp *interp,
+	    const char *cmdName, Tcl_ObjCmdProc2 *proc,
+	    Tcl_ObjCmdProc2 *nreProc2, void *clientData,
+	    Tcl_CmdDeleteProc *deleteProc)
+}
+declare 679 {
+    int Tcl_NRCallObjProc2(Tcl_Interp *interp, Tcl_ObjCmdProc2 *objProc2,
+	    void *clientData, size_t objc, Tcl_Obj *const objv[])
+}
 
 # ----- BASELINE -- FOR -- 8.7.0 ----- #
 
diff --git a/generic/tcl.h b/generic/tcl.h
index ca68eaa..101ae0b 100644
--- a/generic/tcl.h
+++ b/generic/tcl.h
@@ -678,6 +678,9 @@ typedef void (Tcl_CmdTraceProc) (ClientData clientData, Tcl_Interp *interp,
 typedef int (Tcl_CmdObjTraceProc) (ClientData clientData, Tcl_Interp *interp,
 	int level, const char *command, Tcl_Command commandInfo, int objc,
 	struct Tcl_Obj *const *objv);
+typedef int (Tcl_CmdObjTraceProc2) (void *clientData, Tcl_Interp *interp,
+	int level, const char *command, Tcl_Command commandInfo, size_t objc,
+	struct Tcl_Obj *const objv[]);
 typedef void (Tcl_CmdObjTraceDeleteProc) (ClientData clientData);
 typedef void (Tcl_DupInternalRepProc) (struct Tcl_Obj *srcPtr,
 	struct Tcl_Obj *dupPtr);
@@ -702,6 +705,8 @@ typedef int (Tcl_MathProc) (ClientData clientData, Tcl_Interp *interp,
 typedef void (Tcl_NamespaceDeleteProc) (ClientData clientData);
 typedef int (Tcl_ObjCmdProc) (ClientData clientData, Tcl_Interp *interp,
 	int objc, struct Tcl_Obj *const *objv);
+typedef int (Tcl_ObjCmdProc2) (void *clientData, Tcl_Interp *interp,
+	size_t objc, struct Tcl_Obj *const *objv);
 typedef int (Tcl_LibraryInitProc) (Tcl_Interp *interp);
 typedef int (Tcl_LibraryUnloadProc) (Tcl_Interp *interp, int flags);
 typedef void (Tcl_PanicProc) (const char *format, ...);
@@ -921,6 +926,8 @@ typedef struct Tcl_CmdInfo {
 				 * change a command's namespace; use
 				 * TclRenameCommand or Tcl_Eval (of 'rename')
 				 * to do that. */
+    Tcl_ObjCmdProc2 *objProc2;	/* Not used in Tcl 8.7. */
+    void *objClientData2;	/* Not used in Tcl 8.7. */
 } Tcl_CmdInfo;
 
 /*
diff --git a/generic/tclBasic.c b/generic/tclBasic.c
index a0c5a91..b806c33 100644
--- a/generic/tclBasic.c
+++ b/generic/tclBasic.c
@@ -780,6 +780,7 @@ Tcl_CreateInterp(void)
 	Tcl_MutexUnlock(&cancelLock);
     }
 
+#undef TclObjInterpProc
     if (commandTypeInit == 0) {
         TclRegisterCommandTypeName(TclObjInterpProc, "proc");
         TclRegisterCommandTypeName(TclEnsembleImplementationCmd, "ensemble");
@@ -2689,6 +2690,66 @@ Tcl_CreateCommand(
  *----------------------------------------------------------------------
  */
 
+typedef struct {
+    Tcl_ObjCmdProc2 *proc;
+    void *clientData; /* Arbitrary value to pass to proc function. */
+    Tcl_CmdDeleteProc *deleteProc;
+    void *deleteData; /* Arbitrary value to pass to deleteProc function. */
+    Tcl_ObjCmdProc2 *nreProc;
+} CmdWrapperInfo;
+
+
+static int cmdWrapperProc(void *clientData,
+    Tcl_Interp *interp,
+    int objc,
+    Tcl_Obj * const *objv)
+{
+    CmdWrapperInfo *info = (CmdWrapperInfo *)clientData;
+    if (objc < 0) {
+	objc = -1;
+    }
+    return info->proc(info->clientData, interp, objc, objv);
+}
+
+static void cmdWrapperDeleteProc(void *clientData) {
+    CmdWrapperInfo *info = (CmdWrapperInfo *)clientData;
+
+    clientData = info->deleteData;
+    Tcl_CmdDeleteProc *deleteProc = info->deleteProc;
+    ckfree(info);
+    if (deleteProc != NULL) {
+	deleteProc(clientData);
+    }
+}
+
+Tcl_Command
+Tcl_CreateObjCommand2(
+    Tcl_Interp *interp,		/* Token for command interpreter (returned by
+				 * previous call to Tcl_CreateInterp). */
+    const char *cmdName,	/* Name of command. If it contains namespace
+				 * qualifiers, the new command is put in the
+				 * specified namespace; otherwise it is put in
+				 * the global namespace. */
+    Tcl_ObjCmdProc2 *proc,	/* Object-based function to associate with
+				 * name. */
+    void *clientData,	/* Arbitrary value to pass to object
+				 * function. */
+    Tcl_CmdDeleteProc *deleteProc
+				/* If not NULL, gives a function to call when
+				 * this command is deleted. */
+)
+{
+    CmdWrapperInfo *info = (CmdWrapperInfo *)ckalloc(sizeof(CmdWrapperInfo));
+    info->proc = proc;
+    info->clientData = clientData;
+    info->deleteProc = deleteProc;
+    info->deleteData = clientData;
+
+    return Tcl_CreateObjCommand(interp, cmdName,
+	    (proc ? cmdWrapperProc : NULL),
+	    info, cmdWrapperDeleteProc);
+}
+
 Tcl_Command
 Tcl_CreateObjCommand(
     Tcl_Interp *interp,		/* Token for command interpreter (returned by
@@ -3322,8 +3383,14 @@ Tcl_SetCommandInfoFromToken(
 	}
 	cmdPtr->objClientData = infoPtr->objClientData;
     }
-    cmdPtr->deleteProc = infoPtr->deleteProc;
-    cmdPtr->deleteData = infoPtr->deleteData;
+    if (cmdPtr->deleteProc == cmdWrapperDeleteProc) {
+	CmdWrapperInfo *info = (CmdWrapperInfo *)cmdPtr->deleteData;
+	info->deleteProc = infoPtr->deleteProc;
+	info->deleteData = infoPtr->deleteData;
+    } else {
+	cmdPtr->deleteProc = infoPtr->deleteProc;
+	cmdPtr->deleteData = infoPtr->deleteData;
+    }
     return 1;
 }
 
@@ -3400,10 +3467,15 @@ Tcl_GetCommandInfoFromToken(
     infoPtr->objClientData = cmdPtr->objClientData;
     infoPtr->proc = cmdPtr->proc;
     infoPtr->clientData = cmdPtr->clientData;
-    infoPtr->deleteProc = cmdPtr->deleteProc;
-    infoPtr->deleteData = cmdPtr->deleteData;
+    if (cmdPtr->deleteProc == cmdWrapperDeleteProc) {
+	CmdWrapperInfo *info = (CmdWrapperInfo *)cmdPtr->deleteData;
+	infoPtr->deleteProc = info->deleteProc;
+	infoPtr->deleteData = info->deleteData;
+    } else {
+	infoPtr->deleteProc = cmdPtr->deleteProc;
+	infoPtr->deleteData = cmdPtr->deleteData;
+    }
     infoPtr->namespacePtr = (Tcl_Namespace *) cmdPtr->nsPtr;
-
     return 1;
 }
 
@@ -9100,6 +9172,42 @@ Tcl_NRCallObjProc(
     return TclNRRunCallbacks(interp, TCL_OK, rootPtr);
 }
 
+int wrapperNRObjProc(
+    void *clientData,
+    Tcl_Interp *interp,
+    int objc,
+    Tcl_Obj *const objv[])
+{
+    CmdWrapperInfo *info = (CmdWrapperInfo *)clientData;
+    clientData = info->clientData;
+    Tcl_ObjCmdProc2 *proc = info->proc;
+    ckfree(info);
+    return proc(clientData, interp, objc, objv);
+}
+
+int
+Tcl_NRCallObjProc2(
+    Tcl_Interp *interp,
+    Tcl_ObjCmdProc2 *objProc,
+    void *clientData,
+    size_t objc,
+    Tcl_Obj *const objv[])
+{
+    if (objc > INT_MAX) {
+	Tcl_WrongNumArgs(interp, 1, objv, "?args?");
+	return TCL_ERROR;
+    }
+
+    NRE_callback *rootPtr = TOP_CB(interp);
+    CmdWrapperInfo *info = (CmdWrapperInfo *)ckalloc(sizeof(CmdWrapperInfo));
+    info->clientData = clientData;
+    info->proc = objProc;
+
+    TclNRAddCallback(interp, Dispatch, wrapperNRObjProc, info,
+	    INT2PTR(objc), objv);
+    return TclNRRunCallbacks(interp, TCL_OK, rootPtr);
+}
+
 /*
  *----------------------------------------------------------------------
  *
@@ -9128,6 +9236,50 @@ Tcl_NRCallObjProc(
  *----------------------------------------------------------------------
  */
 
+static int cmdWrapperNreProc(
+    void *clientData,
+    Tcl_Interp *interp,
+    int objc,
+    Tcl_Obj *const objv[])
+{
+    CmdWrapperInfo *info = (CmdWrapperInfo *)clientData;
+    if (objc < 0) {
+	objc = -1;
+    }
+    return info->nreProc(info->clientData, interp, objc, objv);
+}
+
+Tcl_Command
+Tcl_NRCreateCommand2(
+    Tcl_Interp *interp,		/* Token for command interpreter (returned by
+				 * previous call to Tcl_CreateInterp). */
+    const char *cmdName,	/* Name of command. If it contains namespace
+				 * qualifiers, the new command is put in the
+				 * specified namespace; otherwise it is put in
+				 * the global namespace. */
+    Tcl_ObjCmdProc2 *proc,	/* Object-based function to associate with
+				 * name, provides direct access for direct
+				 * calls. */
+    Tcl_ObjCmdProc2 *nreProc,	/* Object-based function to associate with
+				 * name, provides NR implementation */
+    void *clientData,	/* Arbitrary value to pass to object
+				 * function. */
+    Tcl_CmdDeleteProc *deleteProc)
+				/* If not NULL, gives a function to call when
+				 * this command is deleted. */
+{
+    CmdWrapperInfo *info = (CmdWrapperInfo *)ckalloc(sizeof(CmdWrapperInfo));
+    info->proc = proc;
+    info->clientData = clientData;
+    info->nreProc = nreProc;
+    info->deleteProc = deleteProc;
+    info->deleteData = clientData;
+    return Tcl_NRCreateCommand(interp, cmdName,
+	    (proc ? cmdWrapperProc : NULL),
+	    (nreProc ? cmdWrapperNreProc : NULL),
+	    info, cmdWrapperDeleteProc);
+}
+
 Tcl_Command
 Tcl_NRCreateCommand(
     Tcl_Interp *interp,		/* Token for command interpreter (returned by
diff --git a/generic/tclCmdIL.c b/generic/tclCmdIL.c
index 1197b92..cdc302c 100644
--- a/generic/tclCmdIL.c
+++ b/generic/tclCmdIL.c
@@ -19,6 +19,7 @@
 
 #include "tclInt.h"
 #include "tclRegexp.h"
+#include <assert.h>
 
 /*
  * During execution of the "lsort" command, structures of the following type
@@ -2898,10 +2899,15 @@ Tcl_LrepeatObjCmd(
 
     listPtr = Tcl_NewListObj(totalElems, NULL);
     if (totalElems) {
-	List *listRepPtr = ListRepPtr(listPtr);
-
-	listRepPtr->elemCount = elementCount*objc;
-	dataArray = listRepPtr->elements;
+	ListRep listRep;
+	ListObjGetRep(listPtr, &listRep);
+	dataArray = ListRepElementsBase(&listRep);
+	listRep.storePtr->numUsed = totalElems;
+	if (listRep.spanPtr) {
+	    /* Future proofing in case Tcl_NewListObj returns a span */
+	    listRep.spanPtr->spanStart = listRep.storePtr->firstUsed;
+	    listRep.spanPtr->spanLength = listRep.storePtr->numUsed;
+	}
     }
 
     /*
@@ -3081,14 +3087,21 @@ Tcl_LreverseObjCmd(
     }
 
     if (Tcl_IsShared(objv[1])
-	    || (ListRepPtr(objv[1])->refCount > 1)) {	/* Bug 1675044 */
+	|| ListObjRepIsShared(objv[1])) { /* Bug 1675044 */
 	Tcl_Obj *resultObj, **dataArray;
-	List *listRepPtr;
+	ListRep listRep;
 
 	resultObj = Tcl_NewListObj(elemc, NULL);
-	listRepPtr = ListRepPtr(resultObj);
-	listRepPtr->elemCount = elemc;
-	dataArray = listRepPtr->elements;
+
+	/* Modify the internal rep in-place */
+	ListObjGetRep(resultObj, &listRep);
+	listRep.storePtr->numUsed = elemc;
+	dataArray = ListRepElementsBase(&listRep);
+	if (listRep.spanPtr) {
+	    /* Future proofing */
+	    listRep.spanPtr->spanStart = listRep.storePtr->firstUsed;
+	    listRep.spanPtr->spanLength = listRep.storePtr->numUsed;
+	}
 
 	for (i=0,j=elemc-1 ; i<elemc ; i++,j--) {
 	    dataArray[j] = elemv[i];
@@ -4409,12 +4422,12 @@ Tcl_LsortObjCmd(
      */
 
     if (sortInfo.resultCode == TCL_OK) {
-	List *listRepPtr;
+	ListRep listRep;
 	Tcl_Obj **newArray, *objPtr;
 
 	resultPtr = Tcl_NewListObj(sortInfo.numElements * groupSize, NULL);
-	listRepPtr = ListRepPtr(resultPtr);
-	newArray = listRepPtr->elements;
+	ListObjGetRep(resultPtr, &listRep);
+	newArray = ListRepElementsBase(&listRep);
 	if (group) {
 	    for (i=0; elementPtr!=NULL ; elementPtr=elementPtr->nextPtr) {
 		idx = elementPtr->payload.index;
@@ -4443,7 +4456,11 @@ Tcl_LsortObjCmd(
 		Tcl_IncrRefCount(objPtr);
 	    }
 	}
-	listRepPtr->elemCount = i;
+	listRep.storePtr->numUsed = i;
+	if (listRep.spanPtr) {
+	    listRep.spanPtr->spanStart = listRep.storePtr->firstUsed;
+	    listRep.spanPtr->spanLength = listRep.storePtr->numUsed;
+	}
 	Tcl_SetObjResult(interp, resultPtr);
     }
 
diff --git a/generic/tclCompCmdsSZ.c b/generic/tclCompCmdsSZ.c
index 29e48eb..7804bf9 100644
--- a/generic/tclCompCmdsSZ.c
+++ b/generic/tclCompCmdsSZ.c
@@ -2427,7 +2427,7 @@ IssueSwitchJumpTable(
 		 * point to here.
 		 */
 
-		Tcl_SetHashValue(hPtr, CurrentOffset(envPtr) - jumpLocation);
+		Tcl_SetHashValue(hPtr, INT2PTR(CurrentOffset(envPtr) - jumpLocation));
 	    }
 	    Tcl_DStringFree(&buffer);
 	} else {
diff --git a/generic/tclCompile.c b/generic/tclCompile.c
index 80d8a09..2d22dc1 100644
--- a/generic/tclCompile.c
+++ b/generic/tclCompile.c
@@ -2838,9 +2838,13 @@ TclInitByteCode(
 
     /*
      * Compute the total number of bytes needed for this bytecode.
+     *
+     * Note that code bytes need not be aligned but since later elements are we
+     * need to pad anyway, either directly after ByteCode or after codeBytes,
+     * and it's easier and more consistent to do the former.
      */
 
-    structureSize = sizeof(ByteCode);
+    structureSize = TCL_ALIGN(sizeof(ByteCode));  /* align code bytes */
     structureSize += TCL_ALIGN(codeBytes);	  /* align object array */
     structureSize += TCL_ALIGN(objArrayBytes);	  /* align exc range arr */
     structureSize += TCL_ALIGN(exceptArrayBytes); /* align AuxData array */
@@ -2879,7 +2883,7 @@ TclInitByteCode(
     codePtr->maxExceptDepth = envPtr->maxExceptDepth;
     codePtr->maxStackDepth = envPtr->maxStackDepth;
 
-    p += sizeof(ByteCode);
+    p += TCL_ALIGN(sizeof(ByteCode));	/* align code bytes */
     codePtr->codeStart = p;
     memcpy(p, envPtr->codeStart, codeBytes);
 
diff --git a/generic/tclConfig.c b/generic/tclConfig.c
index a145bac..5bffbcb 100644
--- a/generic/tclConfig.c
+++ b/generic/tclConfig.c
@@ -194,7 +194,7 @@ QueryConfigObjCmd(
     ClientData clientData,
     Tcl_Interp *interp,
     int objc,
-    struct Tcl_Obj *const *objv)
+    Tcl_Obj *const *objv)
 {
     QCCD *cdPtr = (QCCD *)clientData;
     Tcl_Obj *pkgName = cdPtr->pkg;
diff --git a/generic/tclDecls.h b/generic/tclDecls.h
index b869c97..3917d0f 100644
--- a/generic/tclDecls.h
+++ b/generic/tclDecls.h
@@ -1975,6 +1975,27 @@ EXTERN const char *	TclUtfAtIndex(const char *src, int index);
 EXTERN Tcl_Obj *	TclGetRange(Tcl_Obj *objPtr, int first, int last);
 /* 673 */
 EXTERN int		TclGetUniChar(Tcl_Obj *objPtr, int index);
+/* Slot 674 is reserved */
+/* Slot 675 is reserved */
+/* 676 */
+EXTERN Tcl_Command	Tcl_CreateObjCommand2(Tcl_Interp *interp,
+				const char *cmdName, Tcl_ObjCmdProc2 *proc2,
+				void *clientData,
+				Tcl_CmdDeleteProc *deleteProc);
+/* 677 */
+EXTERN Tcl_Trace	Tcl_CreateObjTrace2(Tcl_Interp *interp, int level,
+				int flags, Tcl_CmdObjTraceProc2 *objProc2,
+				void *clientData,
+				Tcl_CmdObjTraceDeleteProc *delProc);
+/* 678 */
+EXTERN Tcl_Command	Tcl_NRCreateCommand2(Tcl_Interp *interp,
+				const char *cmdName, Tcl_ObjCmdProc2 *proc,
+				Tcl_ObjCmdProc2 *nreProc2, void *clientData,
+				Tcl_CmdDeleteProc *deleteProc);
+/* 679 */
+EXTERN int		Tcl_NRCallObjProc2(Tcl_Interp *interp,
+				Tcl_ObjCmdProc2 *objProc2, void *clientData,
+				size_t objc, Tcl_Obj *const objv[]);
 
 typedef struct {
     const struct TclPlatStubs *tclPlatStubs;
@@ -2684,6 +2705,12 @@ typedef struct TclStubs {
     const char * (*tclUtfAtIndex) (const char *src, int index); /* 671 */
     Tcl_Obj * (*tclGetRange) (Tcl_Obj *objPtr, int first, int last); /* 672 */
     int (*tclGetUniChar) (Tcl_Obj *objPtr, int index); /* 673 */
+    void (*reserved674)(void);
+    void (*reserved675)(void);
+    Tcl_Command (*tcl_CreateObjCommand2) (Tcl_Interp *interp, const char *cmdName, Tcl_ObjCmdProc2 *proc2, void *clientData, Tcl_CmdDeleteProc *deleteProc); /* 676 */
+    Tcl_Trace (*tcl_CreateObjTrace2) (Tcl_Interp *interp, int level, int flags, Tcl_CmdObjTraceProc2 *objProc2, void *clientData, Tcl_CmdObjTraceDeleteProc *delProc); /* 677 */
+    Tcl_Command (*tcl_NRCreateCommand2) (Tcl_Interp *interp, const char *cmdName, Tcl_ObjCmdProc2 *proc, Tcl_ObjCmdProc2 *nreProc2, void *clientData, Tcl_CmdDeleteProc *deleteProc); /* 678 */
+    int (*tcl_NRCallObjProc2) (Tcl_Interp *interp, Tcl_ObjCmdProc2 *objProc2, void *clientData, size_t objc, Tcl_Obj *const objv[]); /* 679 */
 } TclStubs;
 
 extern const TclStubs *tclStubsPtr;
@@ -4062,6 +4089,16 @@ extern const TclStubs *tclStubsPtr;
 	(tclStubsPtr->tclGetRange) /* 672 */
 #define TclGetUniChar \
 	(tclStubsPtr->tclGetUniChar) /* 673 */
+/* Slot 674 is reserved */
+/* Slot 675 is reserved */
+#define Tcl_CreateObjCommand2 \
+	(tclStubsPtr->tcl_CreateObjCommand2) /* 676 */
+#define Tcl_CreateObjTrace2 \
+	(tclStubsPtr->tcl_CreateObjTrace2) /* 677 */
+#define Tcl_NRCreateCommand2 \
+	(tclStubsPtr->tcl_NRCreateCommand2) /* 678 */
+#define Tcl_NRCallObjProc2 \
+	(tclStubsPtr->tcl_NRCallObjProc2) /* 679 */
 
 #endif /* defined(USE_TCL_STUBS) */
 
diff --git a/generic/tclDisassemble.c b/generic/tclDisassemble.c
index 2653630..0bc3de1 100644
--- a/generic/tclDisassemble.c
+++ b/generic/tclDisassemble.c
@@ -301,13 +301,14 @@ DisassembleByteCodeObj(
 
 #ifdef TCL_COMPILE_STATS
     Tcl_AppendPrintfToObj(bufferObj,
-	    "  Code %lu = header %lu+inst %d+litObj %lu+exc %lu+aux %lu+cmdMap %d\n",
-	    (unsigned long) codePtr->structureSize,
-	    (unsigned long) (sizeof(ByteCode) - sizeof(size_t) - sizeof(Tcl_Time)),
+	    "  Code %" TCL_Z_MODIFIER "u = header %" TCL_Z_MODIFIER "u+inst %d+litObj %"
+	    TCL_Z_MODIFIER "u+exc %" TCL_Z_MODIFIER "u+aux %" TCL_Z_MODIFIER "u+cmdMap %d\n",
+	    codePtr->structureSize,
+	    offsetof(ByteCode, localCachePtr),
 	    codePtr->numCodeBytes,
-	    (unsigned long) (codePtr->numLitObjects * sizeof(Tcl_Obj *)),
-	    (unsigned long) (codePtr->numExceptRanges*sizeof(ExceptionRange)),
-	    (unsigned long) (codePtr->numAuxDataItems * sizeof(AuxData)),
+	    codePtr->numLitObjects * sizeof(Tcl_Obj *),
+	    codePtr->numExceptRanges*sizeof(ExceptionRange),
+	    codePtr->numAuxDataItems * sizeof(AuxData),
 	    codePtr->numCmdLocBytes);
 #endif /* TCL_COMPILE_STATS */
 
diff --git a/generic/tclExecute.c b/generic/tclExecute.c
index e292537..8aa3bb2 100644
--- a/generic/tclExecute.c
+++ b/generic/tclExecute.c
@@ -169,11 +169,11 @@ static BuiltinFunc const tclBuiltinFuncTable[] = {
 typedef struct TEBCdata {
     ByteCode *codePtr;		/* Constant until the BC returns */
 				/* -----------------------------------------*/
-    ptrdiff_t *catchTop;	/* These fields are used on return TO this */
+    Tcl_Obj **catchTop;		/* These fields are used on return TO this */
     Tcl_Obj *auxObjList;	/* this level: they record the state when a */
     CmdFrame cmdFrame;		/* new codePtr was received for NR */
                                 /* execution. */
-    void *stack[1];		/* Start of the actual combined catch and obj
+    Tcl_Obj *stack[1];		/* Start of the actual combined catch and obj
 				 * stacks; the struct will be expanded as
 				 * necessary */
 } TEBCdata;
@@ -424,7 +424,7 @@ VarHashCreateVar(
 
 #define OBJ_AT_DEPTH(n)	*(tosPtr-(n))
 
-#define CURR_DEPTH	((ptrdiff_t) (tosPtr - initTosPtr))
+#define CURR_DEPTH	((size_t)(tosPtr - initTosPtr))
 
 #define STACK_BASE(esPtr) ((esPtr)->stackWords - 1)
 
@@ -437,9 +437,9 @@ VarHashCreateVar(
 #ifdef TCL_COMPILE_DEBUG
 #   define TRACE(a) \
     while (traceInstructions) {					\
-	fprintf(stdout, "%2d: %2d (%u) %s ", iPtr->numLevels,	\
-		(int) CURR_DEPTH,				\
-		(unsigned) (pc - codePtr->codeStart),		\
+	fprintf(stdout, "%2d: %2" TCL_Z_MODIFIER "u (%" TCL_Z_MODIFIER "u) %s ", iPtr->numLevels,	\
+		CURR_DEPTH,				\
+		(size_t)(pc - codePtr->codeStart),		\
 		GetOpcodeName(pc));				\
 	printf a;						\
 	break;							\
@@ -453,9 +453,9 @@ VarHashCreateVar(
     TRACE_APPEND(("ERROR: %.30s\n", O2S(Tcl_GetObjResult(interp))));
 #   define TRACE_WITH_OBJ(a, objPtr) \
     while (traceInstructions) {					\
-	fprintf(stdout, "%2d: %2d (%u) %s ", iPtr->numLevels,	\
-		(int) CURR_DEPTH,				\
-		(unsigned) (pc - codePtr->codeStart),		\
+	fprintf(stdout, "%2d: %2" TCL_Z_MODIFIER "u (%" TCL_Z_MODIFIER "u) %s ", iPtr->numLevels,	\
+		CURR_DEPTH,				\
+		(size_t)(pc - codePtr->codeStart),		\
 		GetOpcodeName(pc));				\
 	printf a;						\
 	TclPrintObject(stdout, objPtr, 30);			\
@@ -678,7 +678,7 @@ static const char *	GetOpcodeName(const unsigned char *pc);
 static void		PrintByteCodeInfo(ByteCode *codePtr);
 static const char *	StringForResultCode(int result);
 static void		ValidatePcAndStackTop(ByteCode *codePtr,
-			    const unsigned char *pc, int stackTop,
+			    const unsigned char *pc, size_t stackTop,
 			    int checkStack);
 #endif /* TCL_COMPILE_DEBUG */
 static ByteCode *	CompileExprObj(Tcl_Interp *interp, Tcl_Obj *objPtr);
@@ -1935,8 +1935,8 @@ ArgumentBCEnter(
  *----------------------------------------------------------------------
  */
 #define	bcFramePtr	(&TD->cmdFrame)
-#define	initCatchTop	((ptrdiff_t *) (TD->stack-1))
-#define	initTosPtr	((Tcl_Obj **) (initCatchTop+codePtr->maxExceptDepth))
+#define	initCatchTop	(TD->stack-1)
+#define	initTosPtr	(initCatchTop+codePtr->maxExceptDepth)
 #define esPtr		(iPtr->execEnvPtr->execStackPtr)
 
 int
@@ -2007,7 +2007,7 @@ TclNRExecuteByteCode(
      */
 
     TclNRAddCallback(interp, TEBCresume, TD, /* pc */ NULL,
-	    /* cleanup */ INT2PTR(0), INT2PTR(iPtr->evalFlags));
+	    /* cleanup */ NULL, INT2PTR(iPtr->evalFlags));
 
     /*
      * Reset discard result flag - because it is applicable for this call only,
@@ -2123,7 +2123,7 @@ TEBCresume(
 #ifdef TCL_COMPILE_DEBUG
     if (!pc && (tclTraceExec >= 2)) {
 	PrintByteCodeInfo(codePtr);
-	fprintf(stdout, "  Starting stack top=%d\n", (int) CURR_DEPTH);
+	fprintf(stdout, "  Starting stack top=%" TCL_Z_MODIFIER "u\n", CURR_DEPTH);
 	fflush(stdout);
     }
 #endif
@@ -2327,7 +2327,7 @@ TEBCresume(
 
     CHECK_STACK();
     if (traceInstructions) {
-	fprintf(stdout, "%2d: %2d ", iPtr->numLevels, (int) CURR_DEPTH);
+	fprintf(stdout, "%2d: %2" TCL_Z_MODIFIER "u ", iPtr->numLevels, CURR_DEPTH);
 	TclPrintInstruction(codePtr, pc);
 	fflush(stdout);
     }
@@ -2694,10 +2694,10 @@ TEBCresume(
 	 */
 
 	TclNewObj(objPtr);
-	objPtr->internalRep.twoPtrValue.ptr2 = INT2PTR(CURR_DEPTH);
+	objPtr->internalRep.twoPtrValue.ptr2 = UINT2PTR(CURR_DEPTH);
 	objPtr->length = 0;
 	PUSH_TAUX_OBJ(objPtr);
-	TRACE(("=> mark depth as %d\n", (int) CURR_DEPTH));
+	TRACE(("=> mark depth as %" TCL_Z_MODIFIER "u\n", CURR_DEPTH));
 	NEXT_INST_F(1, 0, 0);
     break;
 
@@ -2709,7 +2709,7 @@ TEBCresume(
 	 */
 
 	CLANG_ASSERT(auxObjList);
-	objc = CURR_DEPTH - PTR2INT(auxObjList->internalRep.twoPtrValue.ptr2);
+	objc = CURR_DEPTH - PTR2UINT(auxObjList->internalRep.twoPtrValue.ptr2);
 	POP_TAUX_OBJ();
 #ifdef TCL_COMPILE_DEBUG
 	/* Ugly abuse! */
@@ -2720,7 +2720,8 @@ TEBCresume(
 
     case INST_EXPAND_STKTOP: {
 	int i;
-	ptrdiff_t moved;
+	TEBCdata *newTD;
+	ptrdiff_t oldCatchTopOff, oldTosPtrOff;
 
 	/*
 	 * Make sure that the element at stackTop is a list; if not, just
@@ -2749,19 +2750,21 @@ TEBCresume(
 		    + codePtr->maxStackDepth /* Beyond the original max */
 		    - CURR_DEPTH;	/* Relative to where we are */
 	    DECACHE_STACK_INFO();
-	    moved = GrowEvaluationStack(iPtr->execEnvPtr, length, 1)
-		    - (Tcl_Obj **) TD;
-	    if (moved) {
+	    oldCatchTopOff = catchTop - initCatchTop;
+	    oldTosPtrOff = tosPtr - initTosPtr;
+	    newTD = (TEBCdata *)
+		    GrowEvaluationStack(iPtr->execEnvPtr, length, 1);
+	    if (newTD != TD) {
 		/*
 		 * Change the global data to point to the new stack: move the
 		 * TEBCdataPtr TD, recompute the position of every other
 		 * stack-allocated parameter, update the stack pointers.
 		 */
 
-		TD = (TEBCdata *) (((Tcl_Obj **)TD) + moved);
+		TD = newTD;
 
-		catchTop += moved;
-		tosPtr += moved;
+		catchTop = initCatchTop + oldCatchTopOff;
+		tosPtr = initTosPtr + oldTosPtrOff;
 	    }
 	}
 
@@ -2813,7 +2816,7 @@ TEBCresume(
 
     case INST_INVOKE_EXPANDED:
 	CLANG_ASSERT(auxObjList);
-	objc = CURR_DEPTH - PTR2INT(auxObjList->internalRep.twoPtrValue.ptr2);
+	objc = CURR_DEPTH - PTR2UINT(auxObjList->internalRep.twoPtrValue.ptr2);
 	POP_TAUX_OBJ();
 	if (objc) {
 	    pcAdjustment = 1;
@@ -3516,7 +3519,7 @@ TEBCresume(
 	    varPtr->value.objPtr = objResultPtr = newValue;
 	    Tcl_IncrRefCount(newValue);
 	}
-	if (Tcl_ListObjReplace(interp, objResultPtr, len, 0, objc, objv)
+	if (TclListObjAppendElements(interp, objResultPtr, objc, objv)
 		!= TCL_OK) {
 	    TRACE_ERROR(interp);
 	    goto gotError;
@@ -3574,7 +3577,7 @@ TEBCresume(
 		} else {
 		    valueToAssign = objResultPtr;
 		}
-		if (Tcl_ListObjReplace(interp, valueToAssign, len, 0,
+		if (TclListObjAppendElements(interp, valueToAssign,
 			objc, objv) != TCL_OK) {
 		    if (createdNewObj) {
 			TclDecrRefCount(valueToAssign);
@@ -4789,7 +4792,11 @@ TEBCresume(
 	    Method *const mPtr =
 		    contextPtr->callPtr->chain[newDepth].mPtr;
 
-	    return mPtr->typePtr->callProc(mPtr->clientData, interp,
+	    if (mPtr->typePtr->version < TCL_OO_METHOD_VERSION_2) {
+		return mPtr->typePtr->callProc(mPtr->clientData, interp,
+			(Tcl_ObjectContext) contextPtr, opnd, objv);
+	    }
+	    return ((Tcl_MethodCallProc2 *)(void *)(mPtr->typePtr->callProc))(mPtr->clientData, interp,
 		    (Tcl_ObjectContext) contextPtr, opnd, objv);
 	}
 
@@ -5994,7 +6001,7 @@ TEBCresume(
 		     * Handle shifts within the native long range.
 		     */
 
-		    if (((size_t) shift < CHAR_BIT*sizeof(long))
+		    if (((size_t)shift < CHAR_BIT*sizeof(long))
 			    && !((w1>0 ? w1 : ~w1) &
 				-(1UL<<(CHAR_BIT*sizeof(long) - 1 - shift)))) {
 			wResult = (Tcl_WideUInt)w1 << shift;
@@ -6801,10 +6808,10 @@ TEBCresume(
 	 * stack.
 	 */
 
-	*(++catchTop) = CURR_DEPTH;
-	TRACE(("%u => catchTop=%d, stackTop=%d\n",
-		TclGetUInt4AtPtr(pc+1), (int) (catchTop - initCatchTop - 1),
-		(int) CURR_DEPTH));
+	*(++catchTop) = (Tcl_Obj *)UINT2PTR(CURR_DEPTH);
+	TRACE(("%u => catchTop=%" TCL_Z_MODIFIER "u, stackTop=%" TCL_Z_MODIFIER "u\n",
+		TclGetUInt4AtPtr(pc+1), (size_t)(catchTop - initCatchTop - 1),
+		CURR_DEPTH));
 	NEXT_INST_F(5, 0, 0);
     break;
 
@@ -6814,7 +6821,7 @@ TEBCresume(
 	Tcl_ResetResult(interp);
 	CACHE_STACK_INFO();
 	result = TCL_OK;
-	TRACE(("=> catchTop=%d\n", (int) (catchTop - initCatchTop - 1)));
+	TRACE(("=> catchTop=%" TCL_Z_MODIFIER "u\n", (size_t)(catchTop - initCatchTop - 1)));
 	NEXT_INST_F(1, 0, 0);
     break;
 
@@ -7713,8 +7720,8 @@ TEBCresume(
 
 	while (auxObjList) {
 	    if ((catchTop != initCatchTop)
-		    && (*catchTop > (ptrdiff_t)
-			auxObjList->internalRep.twoPtrValue.ptr2)) {
+		    && (PTR2UINT(*catchTop) >
+			PTR2UINT(auxObjList->internalRep.twoPtrValue.ptr2))) {
 		break;
 	    }
 	    POP_TAUX_OBJ();
@@ -7789,16 +7796,16 @@ TEBCresume(
 	 */
 
     processCatch:
-	while (CURR_DEPTH > *catchTop) {
+	while (CURR_DEPTH > PTR2UINT(*catchTop)) {
 	    valuePtr = POP_OBJECT();
 	    TclDecrRefCount(valuePtr);
 	}
 #ifdef TCL_COMPILE_DEBUG
 	if (traceInstructions) {
-	    fprintf(stdout, "  ... found catch at %d, catchTop=%d, "
-		    "unwound to %ld, new pc %u\n",
-		    rangePtr->codeOffset, (int) (catchTop - initCatchTop - 1),
-		    (long)*catchTop, (unsigned) rangePtr->catchOffset);
+	    fprintf(stdout, "  ... found catch at %d, catchTop=%" TCL_Z_MODIFIER "u, "
+		    "unwound to %" TCL_Z_MODIFIER "u, new pc %" TCL_Z_MODIFIER "u\n",
+		    rangePtr->codeOffset, (size_t)(catchTop - initCatchTop - 1),
+		    PTR2UINT(*catchTop), (size_t)rangePtr->catchOffset);
 	}
 #endif
 	pc = (codePtr->codeStart + rangePtr->catchOffset);
@@ -7834,10 +7841,10 @@ TEBCresume(
 
 	if (tosPtr < initTosPtr) {
 	    fprintf(stderr,
-		    "\nTclNRExecuteByteCode: abnormal return at pc %u: "
-		    "stack top %d < entry stack top %d\n",
-		    (unsigned)(pc - codePtr->codeStart),
-		    (unsigned) CURR_DEPTH, (unsigned) 0);
+		    "\nTclNRExecuteByteCode: abnormal return at pc %" TCL_Z_MODIFIER "u: "
+		    "stack top %" TCL_Z_MODIFIER "u < entry stack top %d\n",
+		    (size_t)(pc - codePtr->codeStart),
+		    CURR_DEPTH, 0);
 	    Tcl_Panic("TclNRExecuteByteCode execution failure: end stack top < start stack top");
 	}
 	CLANG_ASSERT(bcFramePtr);
@@ -9076,7 +9083,7 @@ PrintByteCodeInfo(
 #ifdef TCL_COMPILE_STATS
     fprintf(stdout, "  Code %lu = header %lu+inst %d+litObj %lu+exc %lu+aux %lu+cmdMap %d\n",
 	    (unsigned long) codePtr->structureSize,
-	    (unsigned long) (sizeof(ByteCode)-sizeof(size_t)-sizeof(Tcl_Time)),
+	    (unsigned long) offsetof(ByteCode, localCachePtr),
 	    codePtr->numCodeBytes,
 	    (unsigned long) (codePtr->numLitObjects * sizeof(Tcl_Obj *)),
 	    (unsigned long) (codePtr->numExceptRanges*sizeof(ExceptionRange)),
@@ -9118,21 +9125,21 @@ ValidatePcAndStackTop(
 				 * stdout. */
     const unsigned char *pc,	/* Points to first byte of a bytecode
 				 * instruction. The program counter. */
-    int stackTop,		/* Current stack top. Must be between
+    size_t stackTop,		/* Current stack top. Must be between
 				 * stackLowerBound and stackUpperBound
 				 * (inclusive). */
     int checkStack)		/* 0 if the stack depth check should be
 				 * skipped. */
 {
-    int stackUpperBound = codePtr->maxStackDepth;
+    size_t stackUpperBound = codePtr->maxStackDepth;
 				/* Greatest legal value for stackTop. */
-    size_t relativePc = (size_t) (pc - codePtr->codeStart);
-    size_t codeStart = (size_t) codePtr->codeStart;
+    size_t relativePc = (size_t)(pc - codePtr->codeStart);
+    size_t codeStart = (size_t)codePtr->codeStart;
     size_t codeEnd = (size_t)
 	    (codePtr->codeStart + codePtr->numCodeBytes);
     unsigned char opCode = *pc;
 
-    if (((size_t) pc < codeStart) || ((size_t) pc > codeEnd)) {
+    if ((PTR2UINT(pc) < codeStart) || (PTR2UINT(pc) > codeEnd)) {
 	fprintf(stderr, "\nBad instruction pc 0x%p in TclNRExecuteByteCode\n",
 		pc);
 	Tcl_Panic("TclNRExecuteByteCode execution failure: bad pc");
@@ -9143,11 +9150,11 @@ ValidatePcAndStackTop(
 	Tcl_Panic("TclNRExecuteByteCode execution failure: bad opcode");
     }
     if (checkStack &&
-	    ((stackTop < 0) || (stackTop > stackUpperBound))) {
+	    (stackTop > stackUpperBound)) {
 	int numChars;
 	const char *cmd = GetSrcInfoForPc(pc, codePtr, &numChars, NULL, NULL);
 
-	fprintf(stderr, "\nBad stack top %d at pc %" TCL_Z_MODIFIER "u in TclNRExecuteByteCode (min 0, max %i)",
+	fprintf(stderr, "\nBad stack top %" TCL_Z_MODIFIER "u at pc %" TCL_Z_MODIFIER "u in TclNRExecuteByteCode (min 0, max %" TCL_Z_MODIFIER "u)",
 		stackTop, relativePc, stackUpperBound);
 	if (cmd != NULL) {
 	    Tcl_Obj *message;
@@ -9719,7 +9726,7 @@ EvalStatsCmd(
     numCurrentByteCodes =
 	    statsPtr->numCompilations - statsPtr->numByteCodesFreed;
     currentHeaderBytes = numCurrentByteCodes
-	    * (sizeof(ByteCode) - sizeof(size_t) - sizeof(Tcl_Time));
+	    * offsetof(ByteCode, localCachePtr);
     literalMgmtBytes = sizeof(LiteralTable)
 	    + (iPtr->literalTable.numBuckets * sizeof(LiteralEntry *))
 	    + (iPtr->literalTable.numEntries * sizeof(LiteralEntry));
diff --git a/generic/tclHash.c b/generic/tclHash.c
index 606d26b..37e45e7 100644
--- a/generic/tclHash.c
+++ b/generic/tclHash.c
@@ -685,21 +685,16 @@ AllocArrayEntry(
     Tcl_HashTable *tablePtr,	/* Hash table. */
     void *keyPtr)			/* Key to store in the hash table entry. */
 {
-    int *array = (int *) keyPtr;
-    int *iPtr1, *iPtr2;
     Tcl_HashEntry *hPtr;
-    int count = tablePtr->keyType;
-    TCL_HASH_TYPE size = sizeof(Tcl_HashEntry) + (count*sizeof(int)) - sizeof(hPtr->key);
+    TCL_HASH_TYPE count = tablePtr->keyType * sizeof(int);
+    TCL_HASH_TYPE size = offsetof(Tcl_HashEntry, key) + count;
 
     if (size < sizeof(Tcl_HashEntry)) {
 	size = sizeof(Tcl_HashEntry);
     }
     hPtr = (Tcl_HashEntry *)ckalloc(size);
 
-    for (iPtr1 = array, iPtr2 = hPtr->key.words;
-	    count > 0; count--, iPtr1++, iPtr2++) {
-	*iPtr2 = *iPtr1;
-    }
+    memcpy(hPtr->key.string, keyPtr, count);
     Tcl_SetHashValue(hPtr, NULL);
 
     return hPtr;
@@ -727,20 +722,9 @@ CompareArrayKeys(
     void *keyPtr,			/* New key to compare. */
     Tcl_HashEntry *hPtr)	/* Existing key to compare. */
 {
-    const int *iPtr1 = (const int *)keyPtr;
-    const int *iPtr2 = hPtr->key.words;
-    Tcl_HashTable *tablePtr = hPtr->tablePtr;
-    int count;
+    size_t count = hPtr->tablePtr->keyType * sizeof(int);
 
-    for (count = tablePtr->keyType; ; count--, iPtr1++, iPtr2++) {
-	if (count == 0) {
-	    return 1;
-	}
-	if (*iPtr1 != *iPtr2) {
-	    break;
-	}
-    }
-    return 0;
+    return !memcmp(keyPtr, hPtr->key.string, count);
 }
 
 /*
@@ -807,7 +791,7 @@ AllocStringEntry(
 	allocsize = sizeof(hPtr->key);
     }
     hPtr = (Tcl_HashEntry *)ckalloc(offsetof(Tcl_HashEntry, key) + allocsize);
-    memset(hPtr, 0, sizeof(Tcl_HashEntry) + allocsize - sizeof(hPtr->key));
+    memset(hPtr, 0, offsetof(Tcl_HashEntry, key) + allocsize);
     memcpy(hPtr->key.string, string, size);
     Tcl_SetHashValue(hPtr, NULL);
     return hPtr;
diff --git a/generic/tclInt.decls b/generic/tclInt.decls
index 5a9f4f0..8d9ef6c 100644
--- a/generic/tclInt.decls
+++ b/generic/tclInt.decls
@@ -1025,6 +1025,7 @@ declare 256 {
     int	TclPtrUnsetVar(Tcl_Interp *interp, Tcl_Var varPtr, Tcl_Var arrayPtr,
 	    Tcl_Obj *part1Ptr, Tcl_Obj *part2Ptr, int flags)
 }
+
 declare 257 {
     void TclStaticLibrary(Tcl_Interp *interp, const char *prefix,
 	    Tcl_LibraryInitProc *initProc, Tcl_LibraryInitProc *safeInitProc)
@@ -1036,8 +1037,14 @@ declare 258 {
 	    Tcl_Obj *basenameObj)
 }
 
-declare 259 {
-    void TclUnusedStubEntry(void)
+# TIP 625: for unit testing - create list objects with span
+declare 260 {
+    Tcl_Obj *TclListTestObj(int length, int leadingSpace, int endSpace)
+}
+
+# TIP 625: for unit testing - check list invariants
+declare 261 {
+    void TclListObjValidate(Tcl_Interp *interp, Tcl_Obj *listObj)
 }
 
 ##############################################################################
diff --git a/generic/tclInt.h b/generic/tclInt.h
index ac6fb54..a7c5c2c 100644
--- a/generic/tclInt.h
+++ b/generic/tclInt.h
@@ -1439,7 +1439,7 @@ typedef int (CompileProc)(Tcl_Interp *interp, Tcl_Parse *parsePtr,
  */
 
 typedef int (CompileHookProc)(Tcl_Interp *interp,
-	struct CompileEnv *compEnvPtr, ClientData clientData);
+	struct CompileEnv *compEnvPtr, void *clientData);
 
 /*
  * The data structure for a (linked list of) execution stacks.
@@ -2358,22 +2358,34 @@ typedef struct Interp {
 #endif
 
 /*
- * This macro is used to determine the offset needed to safely allocate any
+ * TCL_ALIGN is used to determine the offset needed to safely allocate any
  * data structure in memory. Given a starting offset or size, it "rounds up"
- * or "aligns" the offset to the next 8-byte boundary so that any data
- * structure can be placed at the resulting offset without fear of an
- * alignment error.
+ * or "aligns" the offset to the next aligned (typically 8-byte) boundary so
+ * that any data structure can be placed at the resulting offset without fear
+ * of an alignment error. Note this is clamped to a minimum of 8 for API
+ * compatibility.
  *
  * WARNING!! DO NOT USE THIS MACRO TO ALIGN POINTERS: it will produce the
- * wrong result on platforms that allocate addresses that are divisible by 4
- * or 2. Only use it for offsets or sizes.
+ * wrong result on platforms that allocate addresses that are divisible by a
+ * non-trivial factor of this alignment. Only use it for offsets or sizes.
  *
  * This macro is only used by tclCompile.c in the core (Bug 926445). It
  * however not be made file static, as extensions that touch bytecodes
  * (notably tbcload) require it.
  */
 
-#define TCL_ALIGN(x) (((int)(x) + 7) & ~7)
+struct TclMaxAlignment {
+    char unalign[8];
+    union {
+	long long maxAlignLongLong;
+	double maxAlignDouble;
+	void *maxAlignPointer;
+    } aligned;
+};
+#define TCL_ALIGN_BYTES \
+	offsetof(struct TclMaxAlignment, aligned)
+#define TCL_ALIGN(x) \
+	(((x) + (TCL_ALIGN_BYTES - 1)) & ~(TCL_ALIGN_BYTES - 1))
 
 /*
  * A common panic alert when memory allocation fails.
@@ -2425,59 +2437,211 @@ typedef enum TclEolTranslation {
 #define TCL_INVOKE_NO_TRACEBACK	(1<<2)
 
 /*
- * The structure used as the internal representation of Tcl list objects. This
- * struct is grown (reallocated and copied) as necessary to hold all the
- * list's element pointers. The struct might contain more slots than currently
- * used to hold all element pointers. This is done to make append operations
- * faster.
+ * ListSizeT is the type for holding list element counts. It's defined
+ * simplify sharing source between Tcl8 and Tcl9.
  */
+#if TCL_MAJOR_VERSION > 8
 
-typedef struct List {
-    int refCount;
-    int maxElemCount;		/* Total number of element array slots. */
-    int elemCount;		/* Current number of list elements. */
-    int canonicalFlag;		/* Set if the string representation was
-				 * derived from the list representation. May
-				 * be ignored if there is no string rep at
-				 * all.*/
-    Tcl_Obj *elements[TCLFLEXARRAY];		/* First list element; the struct is grown to
-				 * accommodate all elements. */
-} List;
+typedef size_t ListSizeT;
+
+/*
+ * SSIZE_MAX, NOT SIZE_MAX as negative differences need to be expressed
+ * between values of the ListSizeT type so limit the range to signed
+ */
+#define ListSizeT_MAX ((ListSizeT)PTRDIFF_MAX)
+
+#else
+
+typedef int ListSizeT;
+#define ListSizeT_MAX INT_MAX
 
-#define LIST_MAX \
-	((int)(((size_t)UINT_MAX - offsetof(List, elements))/sizeof(Tcl_Obj *)))
-#define LIST_SIZE(numElems) \
-	(TCL_HASH_TYPE)(offsetof(List, elements) + ((numElems) * sizeof(Tcl_Obj *)))
+#endif
 
 /*
- * Macro used to get the elements of a list object.
+ * ListStore --
+ *
+ * A Tcl list's internal representation is defined through three structures.
+ *
+ * A ListStore struct is a structure that includes a variable size array that
+ * serves as storage for a Tcl list. A contiguous sequence of slots in the
+ * array, the "in-use" area, holds valid pointers to Tcl_Obj values that
+ * belong to one or more Tcl lists. The unused slots before and after these
+ * are free slots that may be used to prepend and append without having to
+ * reallocate the struct. The ListStore may be shared amongst multiple lists
+ * and reference counted.
+ *
+ * A ListSpan struct defines a sequence of slots within a ListStore. This sequence
+ * always lies within the "in-use" area of the ListStore. Like ListStore, the
+ * structure may be shared among multiple lists and is reference counted.
+ *
+ * A ListRep struct holds the internal representation of a Tcl list as stored
+ * in a Tcl_Obj. It is composed of a ListStore and a ListSpan that together
+ * define the content of the list. The ListSpan specifies the range of slots
+ * within the ListStore that hold elements for this list. The ListSpan is
+ * optional in which case the list includes all the "in-use" slots of the
+ * ListStore.
+ *
  */
+typedef struct ListStore {
+    ListSizeT firstUsed;    /* Index of first slot in use within slots[] */
+    ListSizeT numUsed;      /* Number of slots in use (starting firstUsed) */
+    ListSizeT numAllocated; /* Total number of slots[] array slots. */
+    size_t refCount;           /* Number of references to this instance */
+    int flags;              /* LISTSTORE_* flags */
+    Tcl_Obj *slots[TCLFLEXARRAY];      /* Variable size array. Grown as needed */
+} ListStore;
+
+#define LISTSTORE_CANONICAL 0x1 /* All Tcl_Obj's referencing this
+                                   store have their string representation
+                                   derived from the list representation */
+
+/* Max number of elements that can be contained in a list */
+#define LIST_MAX                                               \
+    ((ListSizeT)(((size_t)ListSizeT_MAX - offsetof(ListStore, slots)) \
+		   / sizeof(Tcl_Obj *)))
+/* Memory size needed for a ListStore to hold numSlots_ elements */
+#define LIST_SIZE(numSlots_) \
+	((int)(offsetof(ListStore, slots) + ((numSlots_) * sizeof(Tcl_Obj *))))
+
+/*
+ * ListSpan --
+ * See comments above for ListStore
+ */
+typedef struct ListSpan {
+    ListSizeT spanStart;    /* Starting index of the span */
+    ListSizeT spanLength;   /* Number of elements in the span */
+    size_t refCount;     /* Count of references to this span record */
+} ListSpan;
+#ifndef LIST_SPAN_THRESHOLD /* May be set on build line */
+#define LIST_SPAN_THRESHOLD 101
+#endif
 
-#define ListRepPtr(listPtr) \
-    ((List *) (listPtr)->internalRep.twoPtrValue.ptr1)
+/*
+ * ListRep --
+ * See comments above for ListStore
+ */
+typedef struct ListRep {
+    ListStore *storePtr;/* element array shared amongst different lists */
+    ListSpan *spanPtr;  /* If not NULL, the span holds the range of slots
+                           within *storePtr that contain this list elements. */
+} ListRep;
 
-#define ListObjGetElements(listPtr, objc, objv) \
-    ((objv) = ListRepPtr(listPtr)->elements, \
-     (objc) = ListRepPtr(listPtr)->elemCount)
+/*
+ * Macros used to get access list internal representations.
+ *
+ * Naming conventions:
+ * ListRep* - expect a pointer to a valid ListRep
+ * ListObj* - expect a pointer to a Tcl_Obj whose internal type is known to
+ *            be a list (tclListType). Will crash otherwise.
+ * TclListObj* - expect a pointer to a Tcl_Obj whose internal type may or may not
+ *            be tclListType. These will convert as needed and return error if
+ *            conversion not possible.
+ */
+
+/* Returns the starting slot for this listRep in the contained ListStore */
+#define ListRepStart(listRepPtr_)                               \
+    ((listRepPtr_)->spanPtr ? (listRepPtr_)->spanPtr->spanStart \
+			    : (listRepPtr_)->storePtr->firstUsed)
+
+/* Returns the number of elements in this listRep */
+#define ListRepLength(listRepPtr_)                               \
+    ((listRepPtr_)->spanPtr ? (listRepPtr_)->spanPtr->spanLength \
+			    : (listRepPtr_)->storePtr->numUsed)
+
+/* Returns a pointer to the first slot containing this ListRep elements */
+#define ListRepElementsBase(listRepPtr_) \
+    (&(listRepPtr_)->storePtr->slots[ListRepStart(listRepPtr_)])
+
+/* Stores the number of elements and base address of the element array */
+#define ListRepElements(listRepPtr_, objc_, objv_) \
+    (((objv_) = ListRepElementsBase(listRepPtr_)), \
+     ((objc_) = ListRepLength(listRepPtr_)))
+
+/* Returns 1/0 whether the ListRep's ListStore is shared. */
+#define ListRepIsShared(listRepPtr_) ((listRepPtr_)->storePtr->refCount > 1)
+
+/* Returns a pointer to the ListStore component */
+#define ListObjStorePtr(listObj_) \
+    ((ListStore *)((listObj_)->internalRep.twoPtrValue.ptr1))
+
+/* Returns a pointer to the ListSpan component */
+#define ListObjSpanPtr(listObj_) \
+    ((ListSpan *)((listObj_)->internalRep.twoPtrValue.ptr2))
+
+/* Returns the ListRep internal representaton in a Tcl_Obj */
+#define ListObjGetRep(listObj_, listRepPtr_)                 \
+    do {                                                     \
+	(listRepPtr_)->storePtr = ListObjStorePtr(listObj_); \
+	(listRepPtr_)->spanPtr = ListObjSpanPtr(listObj_);   \
+    } while (0)
 
-#define ListObjLength(listPtr, len) \
-    ((len) = ListRepPtr(listPtr)->elemCount)
+/* Returns the length of the list */
+#define ListObjLength(listObj_, len_)                                         \
+    ((len_) = ListObjSpanPtr(listObj_) ? ListObjSpanPtr(listObj_)->spanLength \
+				       : ListObjStorePtr(listObj_)->numUsed)
 
-#define ListObjIsCanonical(listPtr) \
-    (((listPtr)->bytes == NULL) || ListRepPtr(listPtr)->canonicalFlag)
+/* Returns the starting slot index of this list's elements in the ListStore */
+#define ListObjStart(listObj_)                                      \
+    (ListObjSpanPtr(listObj_) ? ListObjSpanPtr(listObj_)->spanStart \
+			      : ListObjStorePtr(listObj_)->firstUsed)
 
-#define TclListObjGetElementsM(interp, listPtr, objcPtr, objvPtr) \
-    (((listPtr)->typePtr == &tclListType) \
-	    ? ((ListObjGetElements((listPtr), *(objcPtr), *(objvPtr))), TCL_OK)\
-	    : Tcl_ListObjGetElements((interp), (listPtr), (objcPtr), (objvPtr)))
+/* Stores the element count and base address of this list's elements */
+#define ListObjGetElements(listObj_, objc_, objv_) \
+    (((objv_) = &ListObjStorePtr(listObj_)->slots[ListObjStart(listObj_)]), \
+     (ListObjLength(listObj_, (objc_))))
 
-#define TclListObjLengthM(interp, listPtr, lenPtr) \
-    (((listPtr)->typePtr == &tclListType) \
-	    ? ((ListObjLength((listPtr), *(lenPtr))), TCL_OK)\
-	    : Tcl_ListObjLength((interp), (listPtr), (lenPtr)))
+/*
+ * Returns 1/0 whether the internal representation (not the Tcl_Obj itself)
+ * is shared.  Note by intent this only checks for sharing of ListStore,
+ * not spans.
+ */
+#define ListObjRepIsShared(listObj_) (ListObjStorePtr(listObj_)->refCount > 1)
 
-#define TclListObjIsCanonical(listPtr) \
-    (((listPtr)->typePtr == &tclListType) ? ListObjIsCanonical((listPtr)) : 0)
+/*
+ * Certain commands like concat are optimized if an existing string
+ * representation of a list object is known to be in canonical format (i.e.
+ * generated from the list representation). There are three conditions when
+ * this will be the case:
+ * (1) No string representation exists which means it will obviously have
+ * to be generated from the list representation when needed
+ * (2) The ListStore flags is marked canonical. This is done at the time
+ * the string representation is generated from the list IF the list
+ * representation does not have a span (see comments in UpdateStringOfList).
+ * (3) The list representation does not have a span component. This is
+ * because list Tcl_Obj's with spans are always created from existing lists
+ * and never from strings (see SetListFromAny) and thus their string
+ * representation will always be canonical.
+ */
+#define ListObjIsCanonical(listObj_)                             \
+    (((listObj_)->bytes == NULL)                                 \
+     || (ListObjStorePtr(listObj_)->flags & LISTSTORE_CANONICAL) \
+     || ListObjSpanPtr(listObj_) != NULL)
+
+/*
+ * Converts the Tcl_Obj to a list if it isn't one and stores the element
+ * count and base address of this list's elements in objcPtr_ and objvPtr_.
+ * Return TCL_OK on success or TCL_ERROR if the Tcl_Obj cannot be
+ * converted to a list.
+ */
+#define TclListObjGetElementsM(interp_, listObj_, objcPtr_, objvPtr_)    \
+    (((listObj_)->typePtr == &tclListType)                              \
+	 ? ((ListObjGetElements((listObj_), *(objcPtr_), *(objvPtr_))), \
+	    TCL_OK)                                                     \
+	 : Tcl_ListObjGetElements(                                      \
+	     (interp_), (listObj_), (objcPtr_), (objvPtr_)))
+
+/*
+ * Converts the Tcl_Obj to a list if it isn't one and stores the element
+ * count in lenPtr_.  Returns TCL_OK on success or TCL_ERROR if the
+ * Tcl_Obj cannot be converted to a list.
+ */
+#define TclListObjLengthM(interp_, listObj_, lenPtr_)         \
+    (((listObj_)->typePtr == &tclListType)                   \
+	 ? ((ListObjLength((listObj_), *(lenPtr_))), TCL_OK) \
+	 : Tcl_ListObjLength((interp_), (listObj_), (lenPtr_)))
+
+#define TclListObjIsCanonical(listObj_) \
+    (((listObj_)->typePtr == &tclListType) ? ListObjIsCanonical((listObj_)) : 0)
 
 /*
  * Modes for collecting (or not) in the implementations of TclNRForeachCmd,
@@ -2583,7 +2747,7 @@ typedef struct List {
  */
 
 #define TCL_FILESYSTEM_VERSION_2	((Tcl_FSVersion) 0x2)
-typedef ClientData (TclFSGetCwdProc2)(ClientData clientData);
+typedef void *(TclFSGetCwdProc2)(void *clientData);
 typedef int (Tcl_FSLoadFileProc2) (Tcl_Interp *interp, Tcl_Obj *pathPtr,
 	Tcl_LoadHandle *handlePtr, Tcl_FSUnloadFileProc **unloadProcPtr, int flags);
 
@@ -2745,7 +2909,7 @@ MODULE_SCOPE Tcl_Encoding tclIdentityEncoding;
 
 MODULE_SCOPE Tcl_GetTimeProc *tclGetTimeProcPtr;
 MODULE_SCOPE Tcl_ScaleTimeProc *tclScaleTimeProcPtr;
-MODULE_SCOPE ClientData tclTimeClientData;
+MODULE_SCOPE void *tclTimeClientData;
 
 /*
  * Variables denoting the Tcl object types defined in the core.
@@ -2921,7 +3085,7 @@ MODULE_SCOPE void	TclArgumentBCRelease(Tcl_Interp *interp,
 MODULE_SCOPE void	TclArgumentGet(Tcl_Interp *interp, Tcl_Obj *obj,
 			    CmdFrame **cfPtrPtr, int *wordPtr);
 MODULE_SCOPE int	TclAsyncNotifier(int sigNumber, Tcl_ThreadId threadId,
-			    ClientData clientData, int *flagPtr, int value);
+			    void *clientData, int *flagPtr, int value);
 MODULE_SCOPE void	TclAsyncMarkFromNotifier(void);
 MODULE_SCOPE double	TclBignumToDouble(const void *bignum);
 MODULE_SCOPE int	TclByteArrayMatch(const unsigned char *string,
@@ -2952,7 +3116,7 @@ MODULE_SCOPE int	TclConvertElement(const char *src, int length,
 			    char *dst, int flags);
 MODULE_SCOPE Tcl_Command TclCreateObjCommandInNs(Tcl_Interp *interp,
 			    const char *cmdName, Tcl_Namespace *nsPtr,
-			    Tcl_ObjCmdProc *proc, ClientData clientData,
+			    Tcl_ObjCmdProc *proc, void *clientData,
 			    Tcl_CmdDeleteProc *deleteProc);
 MODULE_SCOPE Tcl_Command TclCreateEnsembleInNs(Tcl_Interp *interp,
 			    const char *name, Tcl_Namespace *nameNamespacePtr,
@@ -2977,9 +3141,9 @@ MODULE_SCOPE Tcl_ObjCmdProc TclFileRenameCmd;
 MODULE_SCOPE Tcl_ObjCmdProc TclFileTempDirCmd;
 MODULE_SCOPE Tcl_ObjCmdProc TclFileTemporaryCmd;
 MODULE_SCOPE void	TclCreateLateExitHandler(Tcl_ExitProc *proc,
-			    ClientData clientData);
+			    void *clientData);
 MODULE_SCOPE void	TclDeleteLateExitHandler(Tcl_ExitProc *proc,
-			    ClientData clientData);
+			    void *clientData);
 MODULE_SCOPE char *	TclDStringAppendObj(Tcl_DString *dsPtr,
 			    Tcl_Obj *objPtr);
 MODULE_SCOPE char *	TclDStringAppendDString(Tcl_DString *dsPtr,
@@ -3034,7 +3198,7 @@ MODULE_SCOPE int	TclGetCompletionCodeFromObj(Tcl_Interp *interp,
 MODULE_SCOPE Proc *	TclGetLambdaFromObj(Tcl_Interp *interp,
 			    Tcl_Obj *objPtr, Tcl_Obj **nsObjPtrPtr);
 MODULE_SCOPE int	TclGetNumberFromObj(Tcl_Interp *interp,
-			    Tcl_Obj *objPtr, ClientData *clientDataPtr,
+			    Tcl_Obj *objPtr, void **clientDataPtr,
 			    int *typePtr);
 MODULE_SCOPE int	TclGetOpenModeEx(Tcl_Interp *interp,
 			    const char *modeString, int *seekFlagPtr,
@@ -3056,16 +3220,16 @@ MODULE_SCOPE int	TclIncrObj(Tcl_Interp *interp, Tcl_Obj *valuePtr,
 			    Tcl_Obj *incrPtr);
 MODULE_SCOPE Tcl_Obj *	TclIncrObjVar2(Tcl_Interp *interp, Tcl_Obj *part1Ptr,
 			    Tcl_Obj *part2Ptr, Tcl_Obj *incrPtr, int flags);
-MODULE_SCOPE int	TclInfoExistsCmd(ClientData dummy, Tcl_Interp *interp,
+MODULE_SCOPE int	TclInfoExistsCmd(void *dummy, Tcl_Interp *interp,
 			    int objc, Tcl_Obj *const objv[]);
-MODULE_SCOPE int	TclInfoCoroutineCmd(ClientData dummy, Tcl_Interp *interp,
+MODULE_SCOPE int	TclInfoCoroutineCmd(void *dummy, Tcl_Interp *interp,
 			    int objc, Tcl_Obj *const objv[]);
 MODULE_SCOPE Tcl_Obj *	TclInfoFrame(Tcl_Interp *interp, CmdFrame *framePtr);
-MODULE_SCOPE int	TclInfoGlobalsCmd(ClientData dummy, Tcl_Interp *interp,
+MODULE_SCOPE int	TclInfoGlobalsCmd(void *dummy, Tcl_Interp *interp,
 			    int objc, Tcl_Obj *const objv[]);
-MODULE_SCOPE int	TclInfoLocalsCmd(ClientData dummy, Tcl_Interp *interp,
+MODULE_SCOPE int	TclInfoLocalsCmd(void *dummy, Tcl_Interp *interp,
 			    int objc, Tcl_Obj *const objv[]);
-MODULE_SCOPE int	TclInfoVarsCmd(ClientData dummy, Tcl_Interp *interp,
+MODULE_SCOPE int	TclInfoVarsCmd(void *dummy, Tcl_Interp *interp,
 			    int objc, Tcl_Obj *const objv[]);
 MODULE_SCOPE void	TclInitAlloc(void);
 MODULE_SCOPE void	TclInitDbCkalloc(void);
@@ -3095,6 +3259,9 @@ MODULE_SCOPE void	TclListLines(Tcl_Obj *listObj, int line, int n,
 MODULE_SCOPE Tcl_Obj *	TclListObjCopy(Tcl_Interp *interp, Tcl_Obj *listPtr);
 MODULE_SCOPE Tcl_Obj *	TclListObjRange(Tcl_Obj *listPtr, int fromIdx,
 			    int toIdx);
+MODULE_SCOPE int	TclListObjAppendElements(Tcl_Interp *interp,
+			    Tcl_Obj *toObj, int elemCount,
+			    Tcl_Obj *const elemObjv[]);
 MODULE_SCOPE Tcl_Obj *	TclLsetList(Tcl_Interp *interp, Tcl_Obj *listPtr,
 			    Tcl_Obj *indexPtr, Tcl_Obj *valuePtr);
 MODULE_SCOPE Tcl_Obj *	TclLsetFlat(Tcl_Interp *interp, Tcl_Obj *listPtr,
@@ -3137,18 +3304,18 @@ MODULE_SCOPE Tcl_Obj *  TclpTempFileNameForLibrary(Tcl_Interp *interp,
 			    Tcl_Obj* pathPtr);
 MODULE_SCOPE Tcl_Obj *	TclNewFSPathObj(Tcl_Obj *dirPtr, const char *addStrRep,
 			    int len);
-MODULE_SCOPE void	TclpAlertNotifier(ClientData clientData);
-MODULE_SCOPE ClientData	TclpNotifierData(void);
+MODULE_SCOPE void	TclpAlertNotifier(void *clientData);
+MODULE_SCOPE void *TclpNotifierData(void);
 MODULE_SCOPE void	TclpServiceModeHook(int mode);
 MODULE_SCOPE void	TclpSetTimer(const Tcl_Time *timePtr);
 MODULE_SCOPE int	TclpWaitForEvent(const Tcl_Time *timePtr);
 MODULE_SCOPE void	TclpCreateFileHandler(int fd, int mask,
-			    Tcl_FileProc *proc, ClientData clientData);
+			    Tcl_FileProc *proc, void *clientData);
 MODULE_SCOPE int	TclpDeleteFile(const void *path);
 MODULE_SCOPE void	TclpDeleteFileHandler(int fd);
 MODULE_SCOPE void	TclpFinalizeCondition(Tcl_Condition *condPtr);
 MODULE_SCOPE void	TclpFinalizeMutex(Tcl_Mutex *mutexPtr);
-MODULE_SCOPE void	TclpFinalizeNotifier(ClientData clientData);
+MODULE_SCOPE void	TclpFinalizeNotifier(void *clientData);
 MODULE_SCOPE void	TclpFinalizePipes(void);
 MODULE_SCOPE void	TclpFinalizeSockets(void);
 MODULE_SCOPE int	TclCreateSocketAddress(Tcl_Interp *interp,
@@ -3156,13 +3323,13 @@ MODULE_SCOPE int	TclCreateSocketAddress(Tcl_Interp *interp,
 			    const char *host, int port, int willBind,
 			    const char **errorMsgPtr);
 MODULE_SCOPE int	TclpThreadCreate(Tcl_ThreadId *idPtr,
-			    Tcl_ThreadCreateProc *proc, ClientData clientData,
+			    Tcl_ThreadCreateProc *proc, void *clientData,
 			    int stackSize, int flags);
 MODULE_SCOPE int	TclpFindVariable(const char *name, int *lengthPtr);
 MODULE_SCOPE void	TclpInitLibraryPath(char **valuePtr,
 			    TCL_HASH_TYPE *lengthPtr, Tcl_Encoding *encodingPtr);
 MODULE_SCOPE void	TclpInitLock(void);
-MODULE_SCOPE ClientData	TclpInitNotifier(void);
+MODULE_SCOPE void *TclpInitNotifier(void);
 MODULE_SCOPE void	TclpInitPlatform(void);
 MODULE_SCOPE void	TclpInitUnlock(void);
 MODULE_SCOPE Tcl_Obj *	TclpObjListVolumes(void);
@@ -3181,7 +3348,7 @@ MODULE_SCOPE int	TclCrossFilesystemCopy(Tcl_Interp *interp,
 MODULE_SCOPE int	TclpMatchInDirectory(Tcl_Interp *interp,
 			    Tcl_Obj *resultPtr, Tcl_Obj *pathPtr,
 			    const char *pattern, Tcl_GlobTypeData *types);
-MODULE_SCOPE ClientData	TclpGetNativeCwd(ClientData clientData);
+MODULE_SCOPE void *TclpGetNativeCwd(void *clientData);
 MODULE_SCOPE Tcl_FSDupInternalRepProc TclNativeDupInternalRep;
 MODULE_SCOPE Tcl_Obj *	TclpObjLink(Tcl_Obj *pathPtr, Tcl_Obj *toPtr,
 			    int linkType);
@@ -3270,7 +3437,7 @@ MODULE_SCOPE int	TclUtfCount(int ch);
     MODULE_SCOPE int	TclUniCharToUCS4(const Tcl_UniChar *, int *);
     MODULE_SCOPE const Tcl_UniChar *TclUCS4Prev(const Tcl_UniChar *, const Tcl_UniChar *);
 #endif
-MODULE_SCOPE Tcl_Obj *	TclpNativeToNormalized(ClientData clientData);
+MODULE_SCOPE Tcl_Obj *	TclpNativeToNormalized(void *clientData);
 MODULE_SCOPE Tcl_Obj *	TclpFilesystemPathType(Tcl_Obj *pathPtr);
 MODULE_SCOPE int	TclpDlopen(Tcl_Interp *interp, Tcl_Obj *pathPtr,
 			    Tcl_LoadHandle *loadHandle,
@@ -3366,60 +3533,60 @@ MODULE_SCOPE int	TclIsSpaceProc(int byte);
  *----------------------------------------------------------------
  */
 
-MODULE_SCOPE int	Tcl_AfterObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_AfterObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_AppendObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_AppendObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_ApplyObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_ApplyObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE Tcl_Command TclInitArrayCmd(Tcl_Interp *interp);
 MODULE_SCOPE Tcl_Command TclInitBinaryCmd(Tcl_Interp *interp);
-MODULE_SCOPE int	Tcl_BreakObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_BreakObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 #if !defined(TCL_NO_DEPRECATED)
-MODULE_SCOPE int	Tcl_CaseObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_CaseObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 #endif
-MODULE_SCOPE int	Tcl_CatchObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_CatchObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_CdObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_CdObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE Tcl_Command TclInitChanCmd(Tcl_Interp *interp);
-MODULE_SCOPE int	TclChanCreateObjCmd(ClientData clientData,
+MODULE_SCOPE int	TclChanCreateObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	TclChanPostEventObjCmd(ClientData clientData,
+MODULE_SCOPE int	TclChanPostEventObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	TclChanPopObjCmd(ClientData clientData,
+MODULE_SCOPE int	TclChanPopObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc, Tcl_Obj *const objv[]);
-MODULE_SCOPE int	TclChanPushObjCmd(ClientData clientData,
+MODULE_SCOPE int	TclChanPushObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc, Tcl_Obj *const objv[]);
 MODULE_SCOPE void	TclClockInit(Tcl_Interp *interp);
 MODULE_SCOPE int	TclClockOldscanObjCmd(
 			    void *clientData, Tcl_Interp *interp,
 			    int objc, Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_CloseObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_CloseObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_ConcatObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_ConcatObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_ContinueObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_ContinueObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE Tcl_TimerToken TclCreateAbsoluteTimerHandler(
 			    Tcl_Time *timePtr, Tcl_TimerProc *proc,
-			    ClientData clientData);
+			    void *clientData);
 MODULE_SCOPE int	TclDefaultBgErrorHandlerObjCmd(
-			    ClientData clientData, Tcl_Interp *interp,
+			    void *clientData, Tcl_Interp *interp,
 			    int objc, Tcl_Obj *const objv[]);
 MODULE_SCOPE Tcl_Command TclInitDictCmd(Tcl_Interp *interp);
 MODULE_SCOPE int	TclDictWithFinish(Tcl_Interp *interp, Var *varPtr,
@@ -3428,236 +3595,236 @@ MODULE_SCOPE int	TclDictWithFinish(Tcl_Interp *interp, Var *varPtr,
 			    Tcl_Obj *const pathv[], Tcl_Obj *keysPtr);
 MODULE_SCOPE Tcl_Obj *	TclDictWithInit(Tcl_Interp *interp, Tcl_Obj *dictPtr,
 			    int pathc, Tcl_Obj *const pathv[]);
-MODULE_SCOPE int	Tcl_DisassembleObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_DisassembleObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 
 /* Assemble command function */
-MODULE_SCOPE int	Tcl_AssembleObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_AssembleObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	TclNRAssembleObjCmd(ClientData clientData,
+MODULE_SCOPE int	TclNRAssembleObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE Tcl_Command TclInitEncodingCmd(Tcl_Interp *interp);
-MODULE_SCOPE int	Tcl_EofObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_EofObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_ErrorObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_ErrorObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_EvalObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_EvalObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_ExecObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_ExecObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_ExitObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_ExitObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_ExprObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_ExprObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_FblockedObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_FblockedObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE int	Tcl_FconfigureObjCmd(
-			    ClientData clientData, Tcl_Interp *interp,
+			    void *clientData, Tcl_Interp *interp,
 			    int objc, Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_FcopyObjCmd(ClientData dummy,
+MODULE_SCOPE int	Tcl_FcopyObjCmd(void *dummy,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE Tcl_Command TclInitFileCmd(Tcl_Interp *interp);
-MODULE_SCOPE int	Tcl_FileEventObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_FileEventObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_FlushObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_FlushObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_ForObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_ForObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_ForeachObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_ForeachObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_FormatObjCmd(ClientData dummy,
+MODULE_SCOPE int	Tcl_FormatObjCmd(void *dummy,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_GetsObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_GetsObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_GlobalObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_GlobalObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_GlobObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_GlobObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_IfObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_IfObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_IncrObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_IncrObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE Tcl_Command TclInitInfoCmd(Tcl_Interp *interp);
-MODULE_SCOPE int	Tcl_InterpObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_InterpObjCmd(void *clientData,
 			    Tcl_Interp *interp, int argc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_JoinObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_JoinObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_LappendObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_LappendObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_LassignObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_LassignObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_LindexObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_LindexObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_LinsertObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_LinsertObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_LlengthObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_LlengthObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_ListObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_ListObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_LmapObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_LmapObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_LoadObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_LoadObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_LpopObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_LpopObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_LrangeObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_LrangeObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_LremoveObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_LremoveObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_LrepeatObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_LrepeatObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_LreplaceObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_LreplaceObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_LreverseObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_LreverseObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_LsearchObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_LsearchObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_LsetObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_LsetObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_LsortObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_LsortObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE Tcl_Command TclInitNamespaceCmd(Tcl_Interp *interp);
-MODULE_SCOPE int	TclNamespaceEnsembleCmd(ClientData dummy,
+MODULE_SCOPE int	TclNamespaceEnsembleCmd(void *dummy,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_OpenObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_OpenObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_PackageObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_PackageObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_PidObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_PidObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE Tcl_Command TclInitPrefixCmd(Tcl_Interp *interp);
-MODULE_SCOPE int	Tcl_PutsObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_PutsObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_PwdObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_PwdObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_ReadObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_ReadObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_RegexpObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_RegexpObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_RegsubObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_RegsubObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_RenameObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_RenameObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_RepresentationCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_RepresentationCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_ReturnObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_ReturnObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_ScanObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_ScanObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_SeekObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_SeekObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_SetObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_SetObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_SplitObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_SplitObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_SocketObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_SocketObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_SourceObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_SourceObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE Tcl_Command TclInitStringCmd(Tcl_Interp *interp);
-MODULE_SCOPE int	Tcl_SubstObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_SubstObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_SwitchObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_SwitchObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_TellObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_TellObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_ThrowObjCmd(ClientData dummy, Tcl_Interp *interp,
+MODULE_SCOPE int	Tcl_ThrowObjCmd(void *dummy, Tcl_Interp *interp,
 			    int objc, Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_TimeObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_TimeObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_TimeRateObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_TimeRateObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_TraceObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_TraceObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_TryObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_TryObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_UnloadObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_UnloadObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_UnsetObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_UnsetObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_UpdateObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_UpdateObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_UplevelObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_UplevelObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_UpvarObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_UpvarObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_VariableObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_VariableObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_VwaitObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_VwaitObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
-MODULE_SCOPE int	Tcl_WhileObjCmd(ClientData clientData,
+MODULE_SCOPE int	Tcl_WhileObjCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 
@@ -3989,103 +4156,103 @@ MODULE_SCOPE int	TclCompileBasicMin2ArgCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
 
-MODULE_SCOPE int	TclInvertOpCmd(ClientData clientData,
+MODULE_SCOPE int	TclInvertOpCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE int	TclCompileInvertOpCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
-MODULE_SCOPE int	TclNotOpCmd(ClientData clientData,
+MODULE_SCOPE int	TclNotOpCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE int	TclCompileNotOpCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
-MODULE_SCOPE int	TclAddOpCmd(ClientData clientData,
+MODULE_SCOPE int	TclAddOpCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE int	TclCompileAddOpCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
-MODULE_SCOPE int	TclMulOpCmd(ClientData clientData,
+MODULE_SCOPE int	TclMulOpCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE int	TclCompileMulOpCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
-MODULE_SCOPE int	TclAndOpCmd(ClientData clientData,
+MODULE_SCOPE int	TclAndOpCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE int	TclCompileAndOpCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
-MODULE_SCOPE int	TclOrOpCmd(ClientData clientData,
+MODULE_SCOPE int	TclOrOpCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE int	TclCompileOrOpCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
-MODULE_SCOPE int	TclXorOpCmd(ClientData clientData,
+MODULE_SCOPE int	TclXorOpCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE int	TclCompileXorOpCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
-MODULE_SCOPE int	TclPowOpCmd(ClientData clientData,
+MODULE_SCOPE int	TclPowOpCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE int	TclCompilePowOpCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
-MODULE_SCOPE int	TclLshiftOpCmd(ClientData clientData,
+MODULE_SCOPE int	TclLshiftOpCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE int	TclCompileLshiftOpCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
-MODULE_SCOPE int	TclRshiftOpCmd(ClientData clientData,
+MODULE_SCOPE int	TclRshiftOpCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE int	TclCompileRshiftOpCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
-MODULE_SCOPE int	TclModOpCmd(ClientData clientData,
+MODULE_SCOPE int	TclModOpCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE int	TclCompileModOpCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
-MODULE_SCOPE int	TclNeqOpCmd(ClientData clientData,
+MODULE_SCOPE int	TclNeqOpCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE int	TclCompileNeqOpCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
-MODULE_SCOPE int	TclStrneqOpCmd(ClientData clientData,
+MODULE_SCOPE int	TclStrneqOpCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE int	TclCompileStrneqOpCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
-MODULE_SCOPE int	TclInOpCmd(ClientData clientData,
+MODULE_SCOPE int	TclInOpCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE int	TclCompileInOpCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
-MODULE_SCOPE int	TclNiOpCmd(ClientData clientData,
+MODULE_SCOPE int	TclNiOpCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE int	TclCompileNiOpCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
-MODULE_SCOPE int	TclMinusOpCmd(ClientData clientData,
+MODULE_SCOPE int	TclMinusOpCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE int	TclCompileMinusOpCmd(Tcl_Interp *interp,
 			    Tcl_Parse *parsePtr, Command *cmdPtr,
 			    struct CompileEnv *envPtr);
-MODULE_SCOPE int	TclDivOpCmd(ClientData clientData,
+MODULE_SCOPE int	TclDivOpCmd(void *clientData,
 			    Tcl_Interp *interp, int objc,
 			    Tcl_Obj *const objv[]);
 MODULE_SCOPE int	TclCompileDivOpCmd(Tcl_Interp *interp,
@@ -5169,7 +5336,7 @@ void Tcl_Panic(const char *, ...) __attribute__((analyzer_noreturn));
 
 typedef struct NRE_callback {
     Tcl_NRPostProc *procPtr;
-    ClientData data[4];
+    void *data[4];
     struct NRE_callback *nextPtr;
 } NRE_callback;
 
@@ -5184,10 +5351,10 @@ typedef struct NRE_callback {
 	NRE_callback *_callbackPtr;					\
 	TCLNR_ALLOC((interp), (_callbackPtr));				\
 	_callbackPtr->procPtr = (postProcPtr);				\
-	_callbackPtr->data[0] = (ClientData)(data0);			\
-	_callbackPtr->data[1] = (ClientData)(data1);			\
-	_callbackPtr->data[2] = (ClientData)(data2);			\
-	_callbackPtr->data[3] = (ClientData)(data3);			\
+	_callbackPtr->data[0] = (void *)(data0);			\
+	_callbackPtr->data[1] = (void *)(data1);			\
+	_callbackPtr->data[2] = (void *)(data2);			\
+	_callbackPtr->data[3] = (void *)(data3);			\
 	_callbackPtr->nextPtr = TOP_CB(interp);				\
 	TOP_CB(interp) = _callbackPtr;					\
     } while (0)
@@ -5211,6 +5378,7 @@ typedef struct NRE_callback {
 #include "tclIntDecls.h"
 #include "tclIntPlatDecls.h"
 
+
 #if !defined(USE_TCL_STUBS) && !defined(TCL_MEM_DEBUG)
 #define Tcl_AttemptAlloc(size)        TclpAlloc(size)
 #define Tcl_AttemptRealloc(ptr, size) TclpRealloc((ptr), (size))
@@ -5242,8 +5410,8 @@ typedef struct NRE_callback {
  * Other externals.
  */
 
-MODULE_SCOPE size_t TclEnvEpoch;	/* Epoch of the tcl environment
-					 * (if changed with tcl-env). */
+MODULE_SCOPE size_t TclEnvEpoch; /* Epoch of the tcl environment
+                                         * (if changed with tcl-env). */
 
 #endif /* _TCLINT */
 
diff --git a/generic/tclIntDecls.h b/generic/tclIntDecls.h
index 33b6883..588a1fa 100644
--- a/generic/tclIntDecls.h
+++ b/generic/tclIntDecls.h
@@ -656,8 +656,13 @@ EXTERN void		TclStaticLibrary(Tcl_Interp *interp,
 /* 258 */
 EXTERN Tcl_Obj *	TclpCreateTemporaryDirectory(Tcl_Obj *dirObj,
 				Tcl_Obj *basenameObj);
-/* 259 */
-EXTERN void		TclUnusedStubEntry(void);
+/* Slot 259 is reserved */
+/* 260 */
+EXTERN Tcl_Obj *	TclListTestObj(int length, int leadingSpace,
+				int endSpace);
+/* 261 */
+EXTERN void		TclListObjValidate(Tcl_Interp *interp,
+				Tcl_Obj *listObj);
 
 typedef struct TclIntStubs {
     int magic;
@@ -922,7 +927,9 @@ typedef struct TclIntStubs {
     int (*tclPtrUnsetVar) (Tcl_Interp *interp, Tcl_Var varPtr, Tcl_Var arrayPtr, Tcl_Obj *part1Ptr, Tcl_Obj *part2Ptr, int flags); /* 256 */
     void (*tclStaticLibrary) (Tcl_Interp *interp, const char *prefix, Tcl_LibraryInitProc *initProc, Tcl_LibraryInitProc *safeInitProc); /* 257 */
     Tcl_Obj * (*tclpCreateTemporaryDirectory) (Tcl_Obj *dirObj, Tcl_Obj *basenameObj); /* 258 */
-    void (*tclUnusedStubEntry) (void); /* 259 */
+    void (*reserved259)(void);
+    Tcl_Obj * (*tclListTestObj) (int length, int leadingSpace, int endSpace); /* 260 */
+    void (*tclListObjValidate) (Tcl_Interp *interp, Tcl_Obj *listObj); /* 261 */
 } TclIntStubs;
 
 extern const TclIntStubs *tclIntStubsPtr;
@@ -1368,8 +1375,11 @@ extern const TclIntStubs *tclIntStubsPtr;
 	(tclIntStubsPtr->tclStaticLibrary) /* 257 */
 #define TclpCreateTemporaryDirectory \
 	(tclIntStubsPtr->tclpCreateTemporaryDirectory) /* 258 */
-#define TclUnusedStubEntry \
-	(tclIntStubsPtr->tclUnusedStubEntry) /* 259 */
+/* Slot 259 is reserved */
+#define TclListTestObj \
+	(tclIntStubsPtr->tclListTestObj) /* 260 */
+#define TclListObjValidate \
+	(tclIntStubsPtr->tclListObjValidate) /* 261 */
 
 #endif /* defined(USE_TCL_STUBS) */
 
@@ -1408,6 +1418,8 @@ extern const TclIntStubs *tclIntStubsPtr;
 #undef TclGuessPackageName
 #undef TclUnusedStubEntry
 #undef TclSetPreInitScript
+#undef TclObjInterpProc
+#define TclObjInterpProc TclGetObjInterpProc()
 #ifndef TCL_NO_DEPRECATED
 #   define TclSetPreInitScript Tcl_SetPreInitScript
 #   define TclGuessPackageName(fileName, pkgName) ((void)fileName,(void)pkgName,0)
diff --git a/generic/tclInterp.c b/generic/tclInterp.c
index 4ce2f31..d51b289 100644
--- a/generic/tclInterp.c
+++ b/generic/tclInterp.c
@@ -12,6 +12,7 @@
  */
 
 #include "tclInt.h"
+#include <assert.h>
 
 /*
  * A pointer to a string that holds an initialization script that if non-NULL
@@ -1822,7 +1823,7 @@ AliasNRCmd(
     int prefc, cmdc, i;
     Tcl_Obj **prefv, **cmdv;
     Tcl_Obj *listPtr;
-    List *listRep;
+    ListRep listRep;
     int flags = TCL_EVAL_INVOKE;
 
     /*
@@ -1834,10 +1835,15 @@ AliasNRCmd(
     prefv = &aliasPtr->objPtr;
     cmdc = prefc + objc - 1;
 
+    /* TODO - encapsulate this into tclListObj.c */
     listPtr = Tcl_NewListObj(cmdc, NULL);
-    listRep = ListRepPtr(listPtr);
-    listRep->elemCount = cmdc;
-    cmdv = listRep->elements;
+    ListObjGetRep(listPtr, &listRep);
+    cmdv = ListRepElementsBase(&listRep);
+    listRep.storePtr->numUsed = cmdc;
+    if (listRep.spanPtr) {
+	listRep.spanPtr->spanStart = listRep.storePtr->firstUsed;
+	listRep.spanPtr->spanLength = listRep.storePtr->numUsed;
+    }
 
     prefv = &aliasPtr->objPtr;
     memcpy(cmdv, prefv, prefc * sizeof(Tcl_Obj *));
diff --git a/generic/tclListObj.c b/generic/tclListObj.c
index c24809e..7a702e0 100644
--- a/generic/tclListObj.c
+++ b/generic/tclListObj.c
@@ -3,9 +3,7 @@
  *
  *	This file contains functions that implement the Tcl list object type.
  *
- * Copyright © 1995-1997 Sun Microsystems, Inc.
- * Copyright © 1998 Scriptics Corporation.
- * Copyright © 2001 Kevin B. Kenny.  All rights reserved.
+ * Copyright © 2022 Ashok P. Nadkarni.  All rights reserved.
  *
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
@@ -15,28 +13,140 @@
 #include <assert.h>
 
 /*
- * Prototypes for functions defined later in this file:
+ * TODO - memmove is fast. Measure at what size we should prefer memmove
+ * (for unshared objects only) in lieu of range operations. On the other
+ * hand, more cache dirtied?
  */
 
-static List *		AttemptNewList(Tcl_Interp *interp, int objc,
-			    Tcl_Obj *const objv[]);
-static List *		NewListInternalRep(int objc, Tcl_Obj *const objv[], int p);
-static void		DupListInternalRep(Tcl_Obj *srcPtr, Tcl_Obj *copyPtr);
-static void		FreeListInternalRep(Tcl_Obj *listPtr);
-static int		SetListFromAny(Tcl_Interp *interp, Tcl_Obj *objPtr);
-static void		UpdateStringOfList(Tcl_Obj *listPtr);
+/*
+ * Macros for validation and bug checking.
+ */
+
+/*
+ * Control whether asserts are enabled. Always enable in debug builds. In non-debug
+ * builds, can be set with cdebug="-DENABLE_LIST_ASSERTS" on the nmake command line.
+ */
+#ifdef ENABLE_LIST_ASSERTS
+# ifdef NDEBUG
+#  undef NDEBUG /* Activate assert() macro */
+# endif
+#else
+# ifndef NDEBUG
+#  define ENABLE_LIST_ASSERTS /* Always activate list asserts in debug mode */
+# endif
+#endif
+
+#ifdef ENABLE_LIST_ASSERTS
+
+#define LIST_ASSERT(cond_) assert(cond_) /* TODO - is there a Tcl-specific one? */
+/*
+ * LIST_INDEX_ASSERT is to catch errors with negative indices and counts
+ * being passed AFTER validation. On Tcl9 length types are unsigned hence
+ * the checks against LIST_MAX. On Tcl8 length types are signed hence the
+ * also checks against 0.
+ */
+#define LIST_INDEX_ASSERT(idxarg_)                                 \
+    do {                                                           \
+	ListSizeT idx_ = (idxarg_); /* To guard against ++ etc. */ \
+	LIST_ASSERT(idx_ >= 0 && idx_ < LIST_MAX);                 \
+    } while (0)
+/* Ditto for counts except upper limit is different */
+#define LIST_COUNT_ASSERT(countarg_)                                   \
+    do {                                                               \
+	ListSizeT count_ = (countarg_); /* To guard against ++ etc. */ \
+	LIST_ASSERT(count_ >= 0 && count_ <= LIST_MAX);                \
+    } while (0)
+
+#else
+
+#define LIST_ASSERT(cond_) ((void) 0)
+#define LIST_INDEX_ASSERT(idx_) ((void) 0)
+#define LIST_COUNT_ASSERT(count_) ((void) 0)
+
+#endif
+
+/* Checks for when caller should have already converted to internal list type */
+#define LIST_ASSERT_TYPE(listObj_) \
+    LIST_ASSERT((listObj_)->typePtr == &tclListType);
+
+
+/*
+ * If ENABLE_LIST_INVARIANTS is enabled (-DENABLE_LIST_INVARIANTS from the
+ * command line), the entire list internal representation is checked for
+ * inconsistencies. This has a non-trivial cost so has to be separately
+ * enabled and not part of assertions checking. However, the test suite does
+ * invoke ListRepValidate directly even without ENABLE_LIST_INVARIANTS.
+ */
+#ifdef ENABLE_LIST_INVARIANTS
+#define LISTREP_CHECK(listRepPtr_) ListRepValidate(listRepPtr_, __FILE__, __LINE__)
+#else
+#define LISTREP_CHECK(listRepPtr_) (void) 0
+#endif
+
+/*
+ * Flags used for controlling behavior of allocation of list
+ * internal representations.
+ *
+ * If the LISTREP_PANIC_ON_FAIL bit is set, the function will panic if
+ * list is too large or memory cannot be allocated. Without the flag
+ * a NULL pointer is returned.
+ *
+ * The LISTREP_SPACE_FAVOR_NONE, LISTREP_SPACE_FAVOR_FRONT,
+ * LISTREP_SPACE_FAVOR_BACK, LISTREP_SPACE_ONLY_BACK flags are used to
+ * control additional space when allocating.
+ * - If none of these flags is present, the exact space requested is
+ *   allocated, nothing more.
+ * - Otherwise, if only LISTREP_FAVOR_FRONT is present, extra space is
+ *   allocated with more towards the front.
+ * - Conversely, if only LISTREP_FAVOR_BACK is present extra space is allocated
+ *   with more to the back.
+ * - If both flags are present (LISTREP_SPACE_FAVOR_NONE), the extra space
+ *   is equally apportioned.
+ * - Finally if LISTREP_SPACE_ONLY_BACK is present, ALL extra space is at
+ *   the back.
+ */
+#define LISTREP_PANIC_ON_FAIL         0x00000001
+#define LISTREP_SPACE_FAVOR_FRONT     0x00000002
+#define LISTREP_SPACE_FAVOR_BACK      0x00000004
+#define LISTREP_SPACE_ONLY_BACK       0x00000008
+#define LISTREP_SPACE_FAVOR_NONE \
+    (LISTREP_SPACE_FAVOR_FRONT | LISTREP_SPACE_FAVOR_BACK)
+#define LISTREP_SPACE_FLAGS                               \
+    (LISTREP_SPACE_FAVOR_FRONT | LISTREP_SPACE_FAVOR_BACK \
+     | LISTREP_SPACE_ONLY_BACK)
+
+/*
+ * Prototypes for non-inline static functions defined later in this file:
+ */
+static int	MemoryAllocationError(Tcl_Interp *, size_t size);
+static int	ListLimitExceededError(Tcl_Interp *);
+static ListStore *ListStoreNew(ListSizeT objc, Tcl_Obj *const objv[], int flags);
+static int	ListRepInit(ListSizeT objc, Tcl_Obj *const objv[], int flags, ListRep *);
+static int	ListRepInitAttempt(Tcl_Interp *,
+		    ListSizeT objc,
+		    Tcl_Obj *const objv[],
+		    ListRep *);
+static void	ListRepClone(ListRep *fromRepPtr, ListRep *toRepPtr, int flags);
+static void	ListRepUnsharedFreeUnreferenced(const ListRep *repPtr);
+static int	TclListObjGetRep(Tcl_Interp *, Tcl_Obj *listPtr, ListRep *repPtr);
+static void	ListRepRange(ListRep *srcRepPtr,
+		    ListSizeT rangeStart,
+		    ListSizeT rangeEnd,
+		    int preserveSrcRep,
+		    ListRep *rangeRepPtr);
+static ListStore *ListStoreReallocate(ListStore *storePtr, ListSizeT numSlots);
+static void	ListRepValidate(const ListRep *repPtr, const char *file,
+		    int lineNum);
+static void	DupListInternalRep(Tcl_Obj *srcPtr, Tcl_Obj *copyPtr);
+static void	FreeListInternalRep(Tcl_Obj *listPtr);
+static int	SetListFromAny(Tcl_Interp *interp, Tcl_Obj *objPtr);
+static void	UpdateStringOfList(Tcl_Obj *listPtr);
 
 /*
  * The structure below defines the list Tcl object type by means of functions
  * that can be invoked by generic object code.
  *
- * The internal representation of a list object is a two-pointer
- * representation. The first pointer designates a List structure that contains
- * an array of pointers to the element objects, together with integers that
- * represent the current element count and the allocated size of the array.
- * The second pointer is normally NULL; during execution of functions in this
- * file that operate on nested sublists, it is occasionally used as working
- * storage to avoid an auxiliary stack.
+ * The internal representation of a list object is ListRep defined in tcl.h.
  */
 
 const Tcl_ObjType tclListType = {
@@ -48,142 +158,905 @@ const Tcl_ObjType tclListType = {
 };
 
 /* Macros to manipulate the List internal rep */
+#define ListRepIncrRefs(repPtr_)            \
+    do {                                    \
+	(repPtr_)->storePtr->refCount++;    \
+	if ((repPtr_)->spanPtr)             \
+	    (repPtr_)->spanPtr->refCount++; \
+    } while (0)
+
+/* Returns number of free unused slots at the back of the ListRep's ListStore */
+#define ListRepNumFreeTail(repPtr_) \
+    ((repPtr_)->storePtr->numAllocated \
+     - ((repPtr_)->storePtr->firstUsed + (repPtr_)->storePtr->numUsed))
 
-#define ListSetInternalRep(objPtr, listRepPtr)				\
-    do {								\
-	Tcl_ObjInternalRep ir;						\
-	ir.twoPtrValue.ptr1 = (listRepPtr);				\
-	ir.twoPtrValue.ptr2 = NULL;					\
-	(listRepPtr)->refCount++;					\
-	Tcl_StoreInternalRep((objPtr), &tclListType, &ir);			\
+/* Returns number of free unused slots at the front of the ListRep's ListStore */
+#define ListRepNumFreeHead(repPtr_) ((repPtr_)->storePtr->firstUsed)
+
+/* Returns a pointer to the slot corresponding to list index listIdx_ */
+#define ListRepSlotPtr(repPtr_, listIdx_) \
+    (&(repPtr_)->storePtr->slots[ListRepStart(repPtr_) + (listIdx_)])
+
+/*
+ * Macros to replace the internal representation in a Tcl_Obj. There are
+ * subtle differences in each so make sure to use the right one to avoid
+ * memory leaks, access to freed memory and the like.
+ *
+ * ListObjStompRep - assumes the Tcl_Obj internal representation can be
+ * overwritten AND that the passed ListRep already has reference counts that
+ * include the reference from the Tcl_Obj. Basically just copies the pointers
+ * and sets the internal Tcl_Obj type to list
+ *
+ * ListObjOverwriteRep - like ListObjOverwriteRep but additionally
+ * increments reference counts on the passed ListRep. Generally used when
+ * the string representation of the Tcl_Obj is not to be modified.
+ *
+ * ListObjReplaceRepAndInvalidate - Like ListObjOverwriteRep but additionally
+ * assumes the Tcl_Obj internal rep is valid (and possibly even same as
+ * passed ListRep) and frees it first. Additionally invalidates the string
+ * representation. Generally used when modifying a Tcl_Obj value.
+ */
+#define ListObjStompRep(objPtr_, repPtr_)                              \
+    do {                                                               \
+	(objPtr_)->internalRep.twoPtrValue.ptr1 = (repPtr_)->storePtr; \
+	(objPtr_)->internalRep.twoPtrValue.ptr2 = (repPtr_)->spanPtr;  \
+	(objPtr_)->typePtr = &tclListType;                             \
     } while (0)
 
-#define ListGetInternalRep(objPtr, listRepPtr)				\
-    do {								\
-	const Tcl_ObjInternalRep *irPtr;					\
-	irPtr = TclFetchInternalRep((objPtr), &tclListType);		\
-	(listRepPtr) = irPtr ? (List *)irPtr->twoPtrValue.ptr1 : NULL;		\
+#define ListObjOverwriteRep(objPtr_, repPtr_) \
+    do {                                      \
+	ListRepIncrRefs(repPtr_);             \
+	ListObjStompRep(objPtr_, repPtr_);    \
     } while (0)
 
-#define ListResetInternalRep(objPtr, listRepPtr) \
-    TclFetchInternalRep((objPtr), &tclListType)->twoPtrValue.ptr1 = (listRepPtr)
+#define ListObjReplaceRepAndInvalidate(objPtr_, repPtr_)           \
+    do {                                                           \
+	/* Note order important, don't use ListObjOverwriteRep! */ \
+	ListRepIncrRefs(repPtr_);                                  \
+	TclFreeInternalRep(objPtr_);                               \
+	TclInvalidateStringRep(objPtr_);                           \
+	ListObjStompRep(objPtr_, repPtr_);                         \
+    } while (0)
+
+/*
+ *------------------------------------------------------------------------
+ *
+ * ListSpanNew --
+ *
+ *    Allocates and initializes memory for a new ListSpan. The reference
+ *    count on the returned struct is 0.
+ *
+ * Results:
+ *    Non-NULL pointer to the allocated ListSpan.
+ *
+ * Side effects:
+ *    The function will panic on memory allocation failure.
+ *
+ *------------------------------------------------------------------------
+ */
+static inline ListSpan *
+ListSpanNew(
+    ListSizeT firstSlot, /* Starting slot index of the span */
+    ListSizeT numSlots)  /* Number of slots covered by the span */
+{
+    ListSpan *spanPtr = (ListSpan *) ckalloc(sizeof(*spanPtr));
+    spanPtr->refCount = 0;
+    spanPtr->spanStart = firstSlot;
+    spanPtr->spanLength = numSlots;
+    return spanPtr;
+}
+
+/*
+ *------------------------------------------------------------------------
+ *
+ * ListSpanDecrRefs --
+ *
+ *   Decrements the reference count on a span, freeing the memory if
+ *   it drops to zero or less.
+ *
+ * Results:
+ *   None.
+ *
+ * Side effects:
+ *   The memory may be freed.
+ *
+ *------------------------------------------------------------------------
+ */
+static inline void
+ListSpanDecrRefs(ListSpan *spanPtr)
+{
+    if (spanPtr->refCount <= 1) {
+	ckfree(spanPtr);
+    } else {
+	spanPtr->refCount -= 1;
+    }
+}
+
+/*
+ *------------------------------------------------------------------------
+ *
+ * ListSpanMerited --
+ *
+ *    Creation of a new list may sometimes be done as a span on existing
+ *    storage instead of allocating new. The tradeoff is that if the
+ *    original list is released, the new span-based list may hold on to
+ *    more memory than desired. This function implements heuristics for
+ *    deciding which option is better.
+ *
+ * Results:
+ *    Returns non-0 if a span-based list is likely to be more optimal
+ *    and 0 if not.
+ *
+ * Side effects:
+ *    None.
+ *
+ *------------------------------------------------------------------------
+ */
+static inline int
+ListSpanMerited(
+    ListSizeT length,                 /* Length of the proposed span */
+    ListSizeT usedStorageLength,      /* Number of slots currently in used */
+    ListSizeT allocatedStorageLength) /* Length of the currently allocation */
+{
+    /*
+     TODO
+     - heuristics thresholds need to be determined
+     - currently, information about the sharing (ref count) of existing
+       storage is not passed. Perhaps it should be. For example if the
+       existing storage has a "large" ref count, then it might make sense
+       to do even a small span.
+     */
 
-#ifndef TCL_MIN_ELEMENT_GROWTH
-#define TCL_MIN_ELEMENT_GROWTH TCL_MIN_GROWTH/sizeof(Tcl_Obj *)
-#endif
+    if (length < LIST_SPAN_THRESHOLD) {
+	return 0;/* No span for small lists */
+    }
+    if (length < (allocatedStorageLength / 2 - allocatedStorageLength / 8)) {
+	return 0; /* No span if less than 3/8 of allocation */
+    }
+    if (length < usedStorageLength / 2) {
+	return 0; /* No span if less than half current storage */
+    }
+
+    return 1;
+}
 
 /*
- *----------------------------------------------------------------------
+ *------------------------------------------------------------------------
  *
- * NewListInternalRep --
+ * ListStoreUpSize --
  *
- *	Creates a 'List' structure with space for 'objc' elements.  'objc' must
- *	be > 0.  If 'objv' is not NULL, The list is initialized with first
- *	'objc' values in that array.  Otherwise the list is initialized to have
- *	0 elements, with space to add 'objc' more.  Flag value 'p' indicates
- *	how to behave on failure.
+ *    For reasons of efficiency, extra space is allocated for a ListStore
+ *    compared to what was requested. This function calculates how many
+ *    slots should actually be allocated for a given request size.
  *
- * Value
+ * Results:
+ *    Number of slots to allocate.
  *
- *	A new 'List' structure with refCount 0. If some failure
- *	prevents this NULL is returned if 'p' is 0 , and 'Tcl_Panic'
- *	is called if it is not.
+ * Side effects:
+ *    None.
  *
- * Effect
+ *------------------------------------------------------------------------
+ */
+static inline ListSizeT
+ListStoreUpSize(ListSizeT numSlotsRequested) {
+    /* TODO -how much extra? May be double only for smaller requests? */
+    return numSlotsRequested < (LIST_MAX / 2) ? 2 * numSlotsRequested
+						 : LIST_MAX;
+}
+
+/*
+ *------------------------------------------------------------------------
  *
- *	The refCount of each value in 'objv' is incremented as it is added
- *	to the list.
+ * ListRepFreeUnreferenced --
  *
- *----------------------------------------------------------------------
+ *    Inline wrapper for ListRepUnsharedFreeUnreferenced that does quick checks
+ *    before calling it.
+ *
+ *    IMPORTANT: this function must not be called on an internal
+ *    representation of a Tcl_Obj that is itself shared.
+ *
+ * Results:
+ *    None.
+ *
+ * Side effects:
+ *    See comments for ListRepUnsharedFreeUnreferenced.
+ *
+ *------------------------------------------------------------------------
+ */
+static inline void
+ListRepFreeUnreferenced(const ListRep *repPtr)
+{
+    if (! ListRepIsShared(repPtr) && repPtr->spanPtr) {
+        /* T:listrep-1.5.1 */
+	ListRepUnsharedFreeUnreferenced(repPtr);
+    }
+}
+
+/*
+ *------------------------------------------------------------------------
+ *
+ * ObjArrayIncrRefs --
+ *
+ *    Increments the reference counts for Tcl_Obj's in a subarray.
+ *
+ * Results:
+ *    None.
+ *
+ * Side effects:
+ *    As above.
+ *
+ *------------------------------------------------------------------------
+ */
+static inline void
+ObjArrayIncrRefs(
+    Tcl_Obj * const *objv,  /* Pointer to the array */
+    ListSizeT startIdx,     /* Starting index of subarray within objv */
+    ListSizeT count)        /* Number of elements in the subarray */
+{
+    Tcl_Obj * const *end;
+    LIST_INDEX_ASSERT(startIdx);
+    LIST_COUNT_ASSERT(count);
+    objv += startIdx;
+    end = objv + count;
+    while (objv < end) {
+	Tcl_IncrRefCount(*objv);
+	++objv;
+    }
+}
+
+/*
+ *------------------------------------------------------------------------
+ *
+ * ObjArrayDecrRefs --
+ *
+ *    Decrements the reference counts for Tcl_Obj's in a subarray.
+ *
+ * Results:
+ *    None.
+ *
+ * Side effects:
+ *    As above.
+ *
+ *------------------------------------------------------------------------
+ */
+static inline void
+ObjArrayDecrRefs(
+    Tcl_Obj * const *objv, /* Pointer to the array */
+    ListSizeT startIdx,    /* Starting index of subarray within objv */
+    ListSizeT count)       /* Number of elements in the subarray */
+{
+    Tcl_Obj * const *end;
+    LIST_INDEX_ASSERT(startIdx);
+    LIST_COUNT_ASSERT(count);
+    objv += startIdx;
+    end = objv + count;
+    while (objv < end) {
+	Tcl_DecrRefCount(*objv);
+	++objv;
+    }
+}
+
+/*
+ *------------------------------------------------------------------------
+ *
+ * ObjArrayCopy --
+ *
+ *    Copies an array of Tcl_Obj* pointers.
+ *
+ * Results:
+ *    None.
+ *
+ * Side effects:
+ *    Reference counts on copied Tcl_Obj's are incremented.
+ *
+ *------------------------------------------------------------------------
+ */
+static inline void
+ObjArrayCopy(
+    Tcl_Obj **to,          /* Destination */
+    ListSizeT count,       /* Number of pointers to copy */
+    Tcl_Obj *const from[]) /* Source array of Tcl_Obj* */
+{
+    Tcl_Obj **end;
+    LIST_COUNT_ASSERT(count);
+    end = to + count;
+    /* TODO - would memmove followed by separate IncrRef loop be faster? */
+    while (to < end) {
+	Tcl_IncrRefCount(*from);
+	*to++ = *from++;
+    }
+}
+
+/*
+ *------------------------------------------------------------------------
+ *
+ * MemoryAllocationError --
+ *
+ *    Generates a memory allocation failure error.
+ *
+ * Results:
+ *    Always TCL_ERROR.
+ *
+ * Side effects:
+ *    Error message and code are stored in the interpreter if not NULL.
+ *
+ *------------------------------------------------------------------------
  */
+static int
+MemoryAllocationError(
+    Tcl_Interp *interp, /* Interpreter for error message. May be NULL */
+    size_t size)        /* Size of attempted allocation that failed */
+{
+    if (interp != NULL) {
+	Tcl_SetObjResult(
+	    interp,
+	    Tcl_ObjPrintf(
+		"list construction failed: unable to alloc %" TCL_LL_MODIFIER
+		"u bytes",
+		(Tcl_WideInt)size));
+	Tcl_SetErrorCode(interp, "TCL", "MEMORY", NULL);
+    }
+    return TCL_ERROR;
+}
+
+/*
+ *------------------------------------------------------------------------
+ *
+ * ListLimitExceeded --
+ *
+ *    Generates an error for exceeding maximum list size.
+ *
+ * Results:
+ *    Always TCL_ERROR.
+ *
+ * Side effects:
+ *    Error message and code are stored in the interpreter if not NULL.
+ *
+ *------------------------------------------------------------------------
+ */
+static int
+ListLimitExceededError(Tcl_Interp *interp)
+{
+    if (interp != NULL) {
+	Tcl_SetObjResult(
+	    interp,
+	    Tcl_NewStringObj("max length of a Tcl list exceeded", -1));
+	Tcl_SetErrorCode(interp, "TCL", "MEMORY", NULL);
+    }
+    return TCL_ERROR;
+}
+
+/*
+ *------------------------------------------------------------------------
+ *
+ * ListRepUnsharedShiftDown --
+ *
+ *    Shifts the "in-use" contents in the ListStore for a ListRep down
+ *    by the given number of slots. The ListStore must be unshared and
+ *    the free space at the front of the storage area must be big enough.
+ *    It is the caller's responsibility to check.
+ *
+ * Results:
+ *    None.
+ *
+ * Side effects:
+ *    The contents of the ListRep's ListStore area are shifted down in the
+ *    storage area. The ListRep's ListSpan is updated accordingly.
+ *
+ *------------------------------------------------------------------------
+ */
+static inline void
+ListRepUnsharedShiftDown(ListRep *repPtr, ListSizeT shiftCount)
+{
+    ListStore *storePtr;
 
-static List *
-NewListInternalRep(
-    int objc,
-    Tcl_Obj *const objv[],
-    int p)
+    LISTREP_CHECK(repPtr);
+    LIST_ASSERT(!ListRepIsShared(repPtr));
+
+    storePtr = repPtr->storePtr;
+
+    LIST_COUNT_ASSERT(shiftCount);
+    LIST_ASSERT(storePtr->firstUsed >= shiftCount);
+
+    memmove(&storePtr->slots[storePtr->firstUsed - shiftCount],
+	    &storePtr->slots[storePtr->firstUsed],
+	    storePtr->numUsed * sizeof(Tcl_Obj *));
+    storePtr->firstUsed -= shiftCount;
+    if (repPtr->spanPtr) {
+	repPtr->spanPtr->spanStart -= shiftCount;
+	LIST_ASSERT(repPtr->spanPtr->spanLength == storePtr->numUsed);
+    } else {
+	/*
+	 * If there was no span, firstUsed must have been 0 (Invariant)
+	 * AND shiftCount must have been 0 (<= firstUsed on call)
+	 * In other words, this would have been a no-op
+	 */
+
+	LIST_ASSERT(storePtr->firstUsed == 0);
+	LIST_ASSERT(shiftCount == 0);
+    }
+
+    LISTREP_CHECK(repPtr);
+}
+
+/*
+ *------------------------------------------------------------------------
+ *
+ * ListRepUnsharedShiftUp --
+ *
+ *    Shifts the "in-use" contents in the ListStore for a ListRep up
+ *    by the given number of slots. The ListStore must be unshared and
+ *    the free space at the back of the storage area must be big enough.
+ *    It is the caller's responsibility to check.
+ *    TODO - this function is not currently used.
+ *
+ * Results:
+ *    None.
+ *
+ * Side effects:
+ *    The contents of the ListRep's ListStore area are shifted up in the
+ *    storage area. The ListRep's ListSpan is updated accordingly.
+ *
+ *------------------------------------------------------------------------
+ */
+#if 0
+static inline void
+ListRepUnsharedShiftUp(ListRep *repPtr, ListSizeT shiftCount)
 {
-    List *listRepPtr;
+    ListStore *storePtr;
+
+    LISTREP_CHECK(repPtr);
+    LIST_ASSERT(!ListRepIsShared(repPtr));
+    LIST_COUNT_ASSERT(shiftCount);
+
+    storePtr = repPtr->storePtr;
+    LIST_ASSERT((storePtr->firstUsed + storePtr->numUsed + shiftCount)
+		<= storePtr->numAllocated);
+
+    memmove(&storePtr->slots[storePtr->firstUsed + shiftCount],
+	    &storePtr->slots[storePtr->firstUsed],
+	    storePtr->numUsed * sizeof(Tcl_Obj *));
+    storePtr->firstUsed += shiftCount;
+    if (repPtr->spanPtr) {
+	repPtr->spanPtr->spanStart += shiftCount;
+    } else {
+	/* No span means entire original list is span */
+	/* Should have been zero before shift - Invariant TBD */
+	LIST_ASSERT(storePtr->firstUsed == shiftCount);
+	repPtr->spanPtr = ListSpanNew(shiftCount, storePtr->numUsed);
+    }
 
-    if (objc <= 0) {
-	Tcl_Panic("NewListInternalRep: expects postive element count");
+    LISTREP_CHECK(repPtr);
+}
+#endif
+
+/*
+ *------------------------------------------------------------------------
+ *
+ * ListRepValidate --
+ *
+ *	Checks all invariants for a ListRep and panics on failure.
+ *	Note this is independent of NDEBUG, assert etc.
+ *
+ * Results:
+ *    None.
+ *
+ * Side effects:
+ *    Panics if any invariant is not met.
+ *
+ *------------------------------------------------------------------------
+ */
+static void
+ListRepValidate(const ListRep *repPtr, const char *file, int lineNum)
+{
+    ListStore *storePtr = repPtr->storePtr;
+    const char *condition;
+
+    (void)storePtr; /* To stop gcc from whining about unused vars */
+
+#define INVARIANT(cond_)        \
+    do {                        \
+	if (!(cond_)) {         \
+	    condition = #cond_; \
+	    goto failure;       \
+	}                       \
+    } while (0)
+
+    /* Separate each condition so line number gives exact reason for failure */
+    INVARIANT(storePtr != NULL);
+    INVARIANT(storePtr->numAllocated >= 0);
+    INVARIANT(storePtr->numAllocated <= LIST_MAX);
+    INVARIANT(storePtr->firstUsed >= 0);
+    INVARIANT(storePtr->firstUsed < storePtr->numAllocated);
+    INVARIANT(storePtr->numUsed >= 0);
+    INVARIANT(storePtr->numUsed <= storePtr->numAllocated);
+    INVARIANT(storePtr->firstUsed <= (storePtr->numAllocated - storePtr->numUsed));
+
+    if (! ListRepIsShared(repPtr)) {
+	/*
+	 * If this is the only reference and there is no span, then store
+	 * occupancy must begin at 0
+	 */
+	INVARIANT(repPtr->spanPtr || repPtr->storePtr->firstUsed == 0);
     }
 
+    INVARIANT(ListRepStart(repPtr) >= storePtr->firstUsed);
+    INVARIANT(ListRepLength(repPtr) <= storePtr->numUsed);
+    INVARIANT(ListRepStart(repPtr) <= (storePtr->firstUsed + storePtr->numUsed - ListRepLength(repPtr)));
+
+#undef INVARIANT
+
+    return;
+
+failure:
+    Tcl_Panic("List internal failure in %s line %d. Condition: %s",
+	      file,
+	      lineNum,
+	      condition);
+}
+
+/*
+ *------------------------------------------------------------------------
+ *
+ * TclListObjValidate --
+ *
+ *    Wrapper around ListRepValidate. Primarily used from test suite.
+ *
+ * Results:
+ *    None.
+ *
+ * Side effects:
+ *    Will panic if internal structure is not consistent or if object
+ *    cannot be converted to a list object.
+ *
+ *------------------------------------------------------------------------
+ */
+void
+TclListObjValidate(Tcl_Interp *interp, Tcl_Obj *listObj)
+{
+    ListRep listRep;
+    if (TclListObjGetRep(interp, listObj, &listRep) != TCL_OK) {
+	Tcl_Panic("Object passed to TclListObjValidate cannot be converted to "
+		  "a list object.");
+    }
+    ListRepValidate(&listRep, __FILE__, __LINE__);
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ListStoreNew --
+ *
+ *	Allocates a new ListStore with space for at least objc elements. objc
+ *	must be > 0.  If objv!=NULL, initializes with the first objc values
+ *	in that array.  If objv==NULL, initalize 0 elements, with space
+ *	to add objc more.
+ *
+ *      Normally the function allocates the exact space requested unless
+ *      the flags arguments has any LISTREP_SPACE_*
+ *      bits set. See the comments for those #defines.
+ *
+ * Results:
+ *      On success, a pointer to the allocated ListStore is returned.
+ *      On allocation failure, panics if LISTREP_PANIC_ON_FAIL is set in
+ *      flags; otherwise returns NULL.
+ *
+ * Side effects:
+ *	The ref counts of the elements in objv are incremented on success
+ *	since the returned ListStore references them.
+ *
+ *----------------------------------------------------------------------
+ */
+static ListStore *
+ListStoreNew(
+    ListSizeT objc,
+    Tcl_Obj *const objv[],
+    int flags)
+{
+    ListStore *storePtr;
+    ListSizeT capacity;
+
     /*
      * First check to see if we'd overflow and try to allocate an object
-     * larger than our memory allocator allows. Note that this is actually a
-     * fairly small value when you're on a serious 64-bit machine, but that
-     * requires API changes to fix. See [Bug 219196] for a discussion.
+     * larger than our memory allocator allows.
      */
-
-    if ((size_t)objc > LIST_MAX) {
-	if (p) {
-	    Tcl_Panic("max length of a Tcl list (%d elements) exceeded",
-		    LIST_MAX);
+    if (objc > LIST_MAX) {
+	if (flags & LISTREP_PANIC_ON_FAIL) {
+	    Tcl_Panic("max length of a Tcl list exceeded");
 	}
 	return NULL;
     }
 
-    listRepPtr = (List *)attemptckalloc(LIST_SIZE(objc));
-    if (listRepPtr == NULL) {
-	if (p) {
+    if (flags & LISTREP_SPACE_FLAGS) {
+	capacity = ListStoreUpSize(objc);
+    } else {
+	capacity = objc;
+    }
+
+    storePtr = (ListStore *)attemptckalloc(LIST_SIZE(capacity));
+    if (storePtr == NULL && capacity != objc) {
+	capacity = objc; /* Try allocating exact size */
+	storePtr = (ListStore *)attemptckalloc(LIST_SIZE(capacity));
+    }
+    if (storePtr == NULL) {
+	if (flags & LISTREP_PANIC_ON_FAIL) {
 	    Tcl_Panic("list creation failed: unable to alloc %u bytes",
 		    LIST_SIZE(objc));
 	}
 	return NULL;
     }
 
-    listRepPtr->canonicalFlag = 0;
-    listRepPtr->refCount = 0;
-    listRepPtr->maxElemCount = objc;
+    storePtr->refCount = 0;
+    storePtr->flags = 0;
+    storePtr->numAllocated = capacity;
+    if (capacity == objc) {
+	storePtr->firstUsed = 0;
+    } else {
+	ListSizeT extra = capacity - objc;
+	int spaceFlags = flags & LISTREP_SPACE_FLAGS;
+	if (spaceFlags == LISTREP_SPACE_ONLY_BACK) {
+	    storePtr->firstUsed = 0;
+	} else if (spaceFlags == LISTREP_SPACE_FAVOR_FRONT) {
+	    /* Leave more space in the front */
+	    storePtr->firstUsed =
+		extra - (extra / 4); /* NOT same as 3*extra/4 */
+	} else if (spaceFlags == LISTREP_SPACE_FAVOR_BACK) {
+	    /* Leave more space in the back */
+	    storePtr->firstUsed = extra / 4;
+	} else {
+	    /* Apportion equally */
+	    storePtr->firstUsed = extra / 2;
+	}
+    }
 
     if (objv) {
-	Tcl_Obj **elemPtrs;
-	int i;
-
-	listRepPtr->elemCount = objc;
-	elemPtrs = listRepPtr->elements;
-	for (i = 0;  i < objc;  i++) {
-	    elemPtrs[i] = objv[i];
-	    Tcl_IncrRefCount(elemPtrs[i]);
-	}
+	storePtr->numUsed = objc;
+	ObjArrayCopy(&storePtr->slots[storePtr->firstUsed], objc, objv);
     } else {
-	listRepPtr->elemCount = 0;
+	storePtr->numUsed = 0;
     }
-    return listRepPtr;
+
+    return storePtr;
+}
+
+/*
+ *------------------------------------------------------------------------
+ *
+ * ListStoreReallocate --
+ *
+ *    Reallocates the memory for a ListStore.
+ *
+ * Results:
+ *    Pointer to the ListStore which may be the same as storePtr or pointer
+ *    to a new block of memory. On reallocation failure, NULL is returned.
+ *
+ *
+ * Side effects:
+ *    The memory pointed to by storePtr is freed if it a new block has to
+ *    be returned.
+ *
+ *
+ *------------------------------------------------------------------------
+ */
+ListStore *
+ListStoreReallocate (ListStore *storePtr, ListSizeT numSlots)
+{
+    ListSizeT newCapacity;
+    ListStore *newStorePtr;
+
+    newCapacity = ListStoreUpSize(numSlots);
+    newStorePtr =
+	(ListStore *)attemptckrealloc(storePtr, LIST_SIZE(newCapacity));
+    if (newStorePtr == NULL) {
+	newCapacity = numSlots;
+	newStorePtr = (ListStore *)attemptckrealloc(storePtr,
+						    LIST_SIZE(newCapacity));
+	if (newStorePtr == NULL)
+	    return NULL;
+    }
+    /* Only the capacity has changed, fix it in the header */
+    newStorePtr->numAllocated = newCapacity;
+    return newStorePtr;
 }
 
 /*
  *----------------------------------------------------------------------
  *
- *  AttemptNewList --
+ * ListRepInit --
+ *
+ *      Initializes a ListRep to hold a list internal representation
+ *      with space for objc elements.
+ *
+ *      objc must be > 0. If objv!=NULL, initializes with the first objc
+ *      values in that array. If objv==NULL, initalize list internal rep to
+ *      have 0 elements, with space to add objc more.
+ *
+ *	Normally the function allocates the exact space requested unless
+ *	the flags arguments has one of the LISTREP_SPACE_* bits set.
+ *	See the comments for those #defines.
  *
- *	Like NewListInternalRep, but additionally sets an error message on failure.
+ *      The reference counts of the ListStore and ListSpan (if present)
+ *	pointed to by the initialized repPtr are set to zero.
+ *	Caller has to manage them as necessary.
+ *
+ * Results:
+ *      On success, TCL_OK is returned with *listRepPtr initialized.
+ *      On failure, panics if LISTREP_PANIC_ON_FAIL is set in flags; otherwise
+ *	returns TCL_ERROR with *listRepPtr fields set to NULL.
+ *
+ * Side effects:
+ *	The ref counts of the elements in objv are incremented since the
+ *	resulting list now refers to them.
  *
  *----------------------------------------------------------------------
  */
+static int
+ListRepInit(
+    ListSizeT objc,
+    Tcl_Obj *const objv[],
+    int flags,
+    ListRep *repPtr
+    )
+{
+    ListStore *storePtr;
 
-static List *
-AttemptNewList(
+    storePtr = ListStoreNew(objc, objv, flags);
+    if (storePtr) {
+	repPtr->storePtr = storePtr;
+	if (storePtr->firstUsed == 0) {
+	    repPtr->spanPtr = NULL;
+	} else {
+	    repPtr->spanPtr =
+		ListSpanNew(storePtr->firstUsed, storePtr->numUsed);
+	}
+	return TCL_OK;
+    }
+    /*
+     * Initialize to keep gcc happy at the call site. Else it complains
+     * about possibly uninitialized use.
+     */
+    repPtr->storePtr = NULL;
+    repPtr->spanPtr = NULL;
+    return TCL_ERROR;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * ListRepInitAttempt --
+ *
+ *	Creates a list internal rep with space for objc elements. See
+ *	ListRepInit for requirements for parameters (in particular objc must
+ *	be > 0). This function only adds error messages to the interpreter if
+ *	not NULL.
+ *
+ *      The reference counts of the ListStore and ListSpan (if present)
+ *	pointed to by the initialized repPtr are set to zero.
+ *	Caller has to manage them as necessary.
+ *
+ * Results:
+ *      On success, TCL_OK is returned with *listRepPtr initialized.
+ *	On allocation failure, returnes TCL_ERROR with an error message
+ *	in the interpreter if non-NULL.
+ *
+ * Side effects:
+ *	The ref counts of the elements in objv are incremented since the
+ *	resulting list now refers to them.
+ *
+ *----------------------------------------------------------------------
+ */
+static int
+ListRepInitAttempt(
     Tcl_Interp *interp,
-    int objc,
-    Tcl_Obj *const objv[])
+    ListSizeT objc,
+    Tcl_Obj *const objv[],
+    ListRep *repPtr)
 {
-    List *listRepPtr = NewListInternalRep(objc, objv, 0);
+    int result = ListRepInit(objc, objv, 0, repPtr);
 
-    if (interp != NULL && listRepPtr == NULL) {
+    if (result != TCL_OK && interp != NULL) {
 	if (objc > LIST_MAX) {
-	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
-		    "max length of a Tcl list (%d elements) exceeded",
-		    LIST_MAX));
+	    ListLimitExceededError(interp);
 	} else {
-	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
-		    "list creation failed: unable to alloc %u bytes",
-		    LIST_SIZE(objc)));
+	    MemoryAllocationError(interp, LIST_SIZE(objc));
 	}
-	Tcl_SetErrorCode(interp, "TCL", "MEMORY", NULL);
     }
-    return listRepPtr;
+    return result;
+}
+
+/*
+ *------------------------------------------------------------------------
+ *
+ * ListRepClone --
+ *
+ *    Does a deep clone of an existing ListRep.
+ *
+ *    Normally the function allocates the exact space needed unless
+ *    the flags arguments has one of the LISTREP_SPACE_* bits set.
+ *    See the comments for those #defines.
+ *
+ * Results:
+ *    None.
+ *
+ * Side effects:
+ *    The toRepPtr location is initialized with the ListStore and ListSpan
+ *    (if needed) containing a copy of the list elements in fromRepPtr.
+ *    The function will panic if memory cannot be allocated.
+ *
+ *------------------------------------------------------------------------
+ */
+static void
+ListRepClone(ListRep *fromRepPtr, ListRep *toRepPtr, int flags)
+{
+    Tcl_Obj **fromObjs;
+    ListSizeT numFrom;
+
+    ListRepElements(fromRepPtr, numFrom, fromObjs);
+    ListRepInit(numFrom, fromObjs, flags | LISTREP_PANIC_ON_FAIL, toRepPtr);
+}
+
+/*
+ *------------------------------------------------------------------------
+ *
+ * ListRepUnsharedFreeUnreferenced --
+ *
+ *    Frees any Tcl_Obj's from the "in-use" area of the ListStore for a
+ *    ListRep that are not actually references from any lists.
+ *
+ *    IMPORTANT: this function must not be called on a shared internal
+ *    representation or the internal representation of a shared Tcl_Obj.
+ *
+ * Results:
+ *    None.
+ *
+ * Side effects:
+ *    The firstUsed and numUsed fields of the ListStore are updated to
+ *    reflect the new "in-use" extent.
+ *
+ *------------------------------------------------------------------------
+ */
+static void ListRepUnsharedFreeUnreferenced(const ListRep *repPtr)
+{
+    ListSizeT count;
+    ListStore *storePtr;
+    ListSpan *spanPtr;
+
+    LIST_ASSERT(!ListRepIsShared(repPtr));
+    LISTREP_CHECK(repPtr);
+
+    storePtr = repPtr->storePtr;
+    spanPtr = repPtr->spanPtr;
+    if (spanPtr == NULL) {
+	LIST_ASSERT(storePtr->firstUsed == 0); /* Invariant TBD */
+	return;
+    }
+
+    /* Collect garbage at front */
+    count = spanPtr->spanStart - storePtr->firstUsed;
+    LIST_COUNT_ASSERT(count);
+    if (count > 0) {
+        /* T:listrep-1.5.1,6.{1:8} */
+	ObjArrayDecrRefs(storePtr->slots, storePtr->firstUsed, count);
+	storePtr->firstUsed = spanPtr->spanStart;
+	LIST_ASSERT(storePtr->numUsed >= count);
+	storePtr->numUsed -= count;
+    }
+
+    /* Collect garbage at back */
+    count = (storePtr->firstUsed + storePtr->numUsed)
+	  - (spanPtr->spanStart + spanPtr->spanLength);
+    LIST_COUNT_ASSERT(count);
+    if (count > 0) {
+        /* T:listrep-6.{1:8} */
+	ObjArrayDecrRefs(
+	    storePtr->slots, spanPtr->spanStart + spanPtr->spanLength, count);
+	LIST_ASSERT(storePtr->numUsed >= count);
+	storePtr->numUsed -= count;
+    }
+
+    LIST_ASSERT(ListRepStart(repPtr) == storePtr->firstUsed);
+    LIST_ASSERT(ListRepLength(repPtr) == storePtr->numUsed);
+    LISTREP_CHECK(repPtr);
 }
 
 /*
@@ -191,20 +1064,23 @@ AttemptNewList(
  *
  * Tcl_NewListObj --
  *
- *	Creates a new list object and adds values to it. When TCL_MEM_DEBUG is
- *	defined, 'Tcl_DbNewListObj' is called instead.
- *
- * Value
+ *	This function is normally called when not debugging: i.e., when
+ *	TCL_MEM_DEBUG is not defined. It creates a new list object from an
+ *	(objc,objv) array: that is, each of the objc elements of the array
+ *	referenced by objv is inserted as an element into a new Tcl object.
  *
- *	A new list 'Tcl_Obj' to which is appended values from 'objv', or if
- *	'objc' is less than or equal to zero, a list 'Tcl_Obj' having no
- *	elements.  The string representation of the new 'Tcl_Obj' is set to
- *	NULL.  The refCount of the list is 0.
+ *	When TCL_MEM_DEBUG is defined, this function just returns the result
+ *	of calling the debugging version Tcl_DbNewListObj.
  *
- * Effect
+ * Results:
+ *	A new list object is returned that is initialized from the object
+ *	pointers in objv. If objc is less than or equal to zero, an empty
+ *	object is returned. The new object's string representation is left
+ *	NULL. The resulting new list object has ref count 0.
  *
- *	The refCount of each elements in 'objv' is incremented as it is added
- *	to the list.
+ * Side effects:
+ *	The ref counts of the elements in objv are incremented since the
+ *	resulting list now refers to them.
  *
  *----------------------------------------------------------------------
  */
@@ -214,7 +1090,7 @@ AttemptNewList(
 
 Tcl_Obj *
 Tcl_NewListObj(
-    int objc,			/* Count of objects referenced by objv. */
+    ListSizeT objc,		/* Count of objects referenced by objv. */
     Tcl_Obj *const objv[])	/* An array of pointers to Tcl objects. */
 {
     return Tcl_DbNewListObj(objc, objv, "unknown", 0);
@@ -224,45 +1100,50 @@ Tcl_NewListObj(
 
 Tcl_Obj *
 Tcl_NewListObj(
-    int objc,			/* Count of objects referenced by objv. */
+    ListSizeT objc,		/* Count of objects referenced by objv. */
     Tcl_Obj *const objv[])	/* An array of pointers to Tcl objects. */
 {
-    List *listRepPtr;
-    Tcl_Obj *listPtr;
+    ListRep listRep;
+    Tcl_Obj *listObj;
 
-    TclNewObj(listPtr);
+    TclNewObj(listObj);
 
     if (objc <= 0) {
-	return listPtr;
+	return listObj;
     }
 
-    /*
-     * Create the internal rep.
-     */
-
-    listRepPtr = NewListInternalRep(objc, objv, 1);
+    ListRepInit(objc, objv, LISTREP_PANIC_ON_FAIL, &listRep);
+    ListObjReplaceRepAndInvalidate(listObj, &listRep);
 
-    /*
-     * Now create the object.
-     */
-
-    TclInvalidateStringRep(listPtr);
-    ListSetInternalRep(listPtr, listRepPtr);
-    return listPtr;
+    return listObj;
 }
 #endif /* if TCL_MEM_DEBUG */
 
 /*
  *----------------------------------------------------------------------
  *
- *  Tcl_DbNewListObj --
+ * Tcl_DbNewListObj --
+ *
+ *	This function is normally called when debugging: i.e., when
+ *	TCL_MEM_DEBUG is defined. It creates new list objects. It is the same
+ *	as the Tcl_NewListObj function above except that it calls
+ *	Tcl_DbCkalloc directly with the file name and line number from its
+ *	caller. This simplifies debugging since then the [memory active]
+ *	command will report the correct file name and line number when
+ *	reporting objects that haven't been freed.
  *
- *	Like 'Tcl_NewListObj', but it calls Tcl_DbCkalloc directly with the
- *	file name and line number from its caller.  This simplifies debugging
- *	since the [memory active] command will report the correct file
- *	name and line number when reporting objects that haven't been freed.
+ *	When TCL_MEM_DEBUG is not defined, this function just returns the
+ *	result of calling Tcl_NewListObj.
  *
- *	When TCL_MEM_DEBUG is not defined, 'Tcl_NewListObj' is called instead.
+ * Results:
+ *	A new list object is returned that is initialized from the object
+ *	pointers in objv. If objc is less than or equal to zero, an empty
+ *	object is returned. The new object's string representation is left
+ *	NULL. The new list object has ref count 0.
+ *
+ * Side effects:
+ *	The ref counts of the elements in objv are incremented since the
+ *	resulting list now refers to them.
  *
  *----------------------------------------------------------------------
  */
@@ -271,43 +1152,33 @@ Tcl_NewListObj(
 
 Tcl_Obj *
 Tcl_DbNewListObj(
-    int objc,			/* Count of objects referenced by objv. */
+    ListSizeT objc,		/* Count of objects referenced by objv. */
     Tcl_Obj *const objv[],	/* An array of pointers to Tcl objects. */
     const char *file,		/* The name of the source file calling this
 				 * function; used for debugging. */
     int line)			/* Line number in the source file; used for
 				 * debugging. */
 {
-    Tcl_Obj *listPtr;
-    List *listRepPtr;
+    Tcl_Obj *listObj;
+    ListRep listRep;
 
-    TclDbNewObj(listPtr, file, line);
+    TclDbNewObj(listObj, file, line);
 
     if (objc <= 0) {
-	return listPtr;
+	return listObj;
     }
 
-    /*
-     * Create the internal rep.
-     */
-
-    listRepPtr = NewListInternalRep(objc, objv, 1);
-
-    /*
-     * Now create the object.
-     */
-
-    TclInvalidateStringRep(listPtr);
-    ListSetInternalRep(listPtr, listRepPtr);
+    ListRepInit(objc, objv, LISTREP_PANIC_ON_FAIL, &listRep);
+    ListObjReplaceRepAndInvalidate(listObj, &listRep);
 
-    return listPtr;
+    return listObj;
 }
 
 #else /* if not TCL_MEM_DEBUG */
 
 Tcl_Obj *
 Tcl_DbNewListObj(
-    int objc,			/* Count of objects referenced by objv. */
+    ListSizeT objc,		/* Count of objects referenced by objv. */
     Tcl_Obj *const objv[],	/* An array of pointers to Tcl objects. */
     TCL_UNUSED(const char *) /*file*/,
     TCL_UNUSED(int) /*line*/)
@@ -317,45 +1188,152 @@ Tcl_DbNewListObj(
 #endif /* TCL_MEM_DEBUG */
 
 /*
+ *------------------------------------------------------------------------
+ *
+ * TclNewListObj2 --
+ *
+ *    Create a new Tcl_Obj list comprising of the concatenation of two
+ *    Tcl_Obj* arrays.
+ *    TODO - currently this function is not used within tclListObj but
+ *    need to see if it would be useful in other files that preallocate
+ *    lists and then append.
+ *
+ * Results:
+ *    Non-NULL pointer to the allocate Tcl_Obj.
+ *
+ * Side effects:
+ *    None.
+ *
+ *------------------------------------------------------------------------
+ */
+Tcl_Obj *
+TclNewListObj2(
+    ListSizeT objc1,		/* Count of objects referenced by objv1. */
+    Tcl_Obj *const objv1[],	/* First array of pointers to Tcl objects. */
+    ListSizeT objc2,		/* Count of objects referenced by objv2. */
+    Tcl_Obj *const objv2[]	/* Second array of pointers to Tcl objects. */
+)
+{
+    Tcl_Obj *listObj;
+    ListStore *storePtr;
+    ListSizeT objc = objc1 + objc2;
+
+    listObj = Tcl_NewListObj(objc, NULL);
+    if (objc == 0) {
+	return listObj; /* An empty object */
+    }
+    LIST_ASSERT_TYPE(listObj);
+
+    storePtr = ListObjStorePtr(listObj);
+
+    LIST_ASSERT(ListObjSpanPtr(listObj) == NULL);
+    LIST_ASSERT(storePtr->firstUsed == 0);
+    LIST_ASSERT(storePtr->numUsed == 0);
+    LIST_ASSERT(storePtr->numAllocated >= objc);
+
+    if (objc1) {
+	ObjArrayCopy(storePtr->slots, objc1, objv1);
+    }
+    if (objc2) {
+	ObjArrayCopy(&storePtr->slots[objc1], objc2, objv2);
+    }
+    storePtr->numUsed = objc;
+    return listObj;
+}
+
+/*
  *----------------------------------------------------------------------
  *
- * Tcl_SetListObj --
+ * TclListObjGetRep --
  *
- *	Like 'Tcl_NewListObj', but operates on an existing 'Tcl_Obj'instead of
- *	creating a new one.
+ *	This function returns a copy of the ListRep stored
+ *	as the internal representation of an object. The reference
+ *	counts of the (ListStore, ListSpan) contained in the representation
+ *	are NOT incremented.
  *
+ * Results:
+ *	The return value is normally TCL_OK; in this case *listRepP
+ *	is set to a copy of the descriptor stored as the internal
+ *	representation of the Tcl_Obj containing a list. if listPtr does not
+ *	refer to a list object and the object can not be converted to one,
+ *	TCL_ERROR is returned and an error message will be left in the
+ *	interpreter's result if interp is not NULL.
+ *
+ * Side effects:
+ *	The possible conversion of the object referenced by listPtr
+ *	to a list object. *repPtr is initialized to the internal rep
+ *      if result is TCL_OK, or set to NULL on error.
  *----------------------------------------------------------------------
  */
 
+static int
+TclListObjGetRep(
+    Tcl_Interp *interp, /* Used to report errors if not NULL. */
+    Tcl_Obj *listObj,   /* List object for which an element array is
+			 * to be returned. */
+    ListRep *repPtr) /* Location to store descriptor */
+{
+    if (!TclHasInternalRep(listObj, &tclListType)) {
+	int result;
+	result = SetListFromAny(interp, listObj);
+	if (result != TCL_OK) {
+	    /* Init to keep gcc happy wrt uninitialized fields at call site */
+	    repPtr->storePtr = NULL;
+	    repPtr->spanPtr = NULL;
+	    return result;
+	}
+    }
+    ListObjGetRep(listObj, repPtr);
+    LISTREP_CHECK(repPtr);
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * Tcl_SetListObj --
+ *
+ *	Modify an object to be a list containing each of the objc elements of
+ *	the object array referenced by objv.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	The object is made a list object and is initialized from the object
+ *	pointers in objv. If objc is less than or equal to zero, an empty
+ *	object is returned. The new object's string representation is left
+ *	NULL. The ref counts of the elements in objv are incremented since the
+ *	list now refers to them. The object's old string and internal
+ *	representations are freed and its type is set NULL.
+ *
+ *----------------------------------------------------------------------
+ */
 void
 Tcl_SetListObj(
     Tcl_Obj *objPtr,		/* Object whose internal rep to init. */
-    int objc,			/* Count of objects referenced by objv. */
+    ListSizeT objc,		/* Count of objects referenced by objv. */
     Tcl_Obj *const objv[])	/* An array of pointers to Tcl objects. */
 {
-    List *listRepPtr;
-
     if (Tcl_IsShared(objPtr)) {
 	Tcl_Panic("%s called with shared object", "Tcl_SetListObj");
     }
 
     /*
-     * Free any old string rep and any internal rep for the old type.
-     */
-
-    TclFreeInternalRep(objPtr);
-    TclInvalidateStringRep(objPtr);
-
-    /*
      * Set the object's type to "list" and initialize the internal rep.
      * However, if there are no elements to put in the list, just give the
-     * object an empty string rep and a NULL type.
+     * object an empty string rep and a NULL type. NOTE ListRepInit must
+     * not be called with objc == 0!
      */
 
     if (objc > 0) {
-	listRepPtr = NewListInternalRep(objc, objv, 1);
-	ListSetInternalRep(objPtr, listRepPtr);
+	ListRep listRep;
+	/* TODO - perhaps ask for extra space? */
+	ListRepInit(objc, objv, LISTREP_PANIC_ON_FAIL, &listRep);
+	ListObjReplaceRepAndInvalidate(objPtr, &listRep);
     } else {
+	TclFreeInternalRep(objPtr);
+	TclInvalidateStringRep(objPtr);
 	Tcl_InitStringRep(objPtr, NULL, 0);
     }
 }
@@ -365,20 +1343,18 @@ Tcl_SetListObj(
  *
  * TclListObjCopy --
  *
- *	Creates a new 'Tcl_Obj' which is a pure copy of a list value. This
- *	provides for the C level a counterpart of the [lrange $list 0 end]
- *	command, while using internals details to be as efficient as possible.
- *
- * Value
+ *	Makes a "pure list" copy of a list value. This provides for the C
+ *	level a counterpart of the [lrange $list 0 end] command, while using
+ *	internals details to be as efficient as possible.
  *
- *	The address of the new 'Tcl_Obj' which shares its internal
- *	representation with 'listPtr', and whose refCount is 0.  If 'listPtr'
- *	is not actually a list, the value is NULL, and an error message is left
- *	in 'interp' if it is not NULL.
- *
- * Effect
+ * Results:
+ *	Normally returns a pointer to a new Tcl_Obj, that contains the same
+ *	list value as *listPtr does. The returned Tcl_Obj has a refCount of
+ *	zero. If *listPtr does not hold a list, NULL is returned, and if
+ *	interp is non-NULL, an error message is recorded there.
  *
- *	'listPtr' is converted to a list if it isn't one already.
+ * Side effects:
+ *	None.
  *
  *----------------------------------------------------------------------
  */
@@ -386,137 +1362,290 @@ Tcl_SetListObj(
 Tcl_Obj *
 TclListObjCopy(
     Tcl_Interp *interp,		/* Used to report errors if not NULL. */
-    Tcl_Obj *listPtr)		/* List object for which an element array is
+    Tcl_Obj *listObj)		/* List object for which an element array is
 				 * to be returned. */
 {
-    Tcl_Obj *copyPtr;
-    List *listRepPtr;
+    Tcl_Obj *copyObj;
 
-    ListGetInternalRep(listPtr, listRepPtr);
-    if (NULL == listRepPtr) {
-	if (SetListFromAny(interp, listPtr) != TCL_OK) {
+    if (!TclHasInternalRep(listObj, &tclListType)) {
+	if (SetListFromAny(interp, listObj) != TCL_OK) {
 	    return NULL;
 	}
     }
 
-    TclNewObj(copyPtr);
-    TclInvalidateStringRep(copyPtr);
-    DupListInternalRep(listPtr, copyPtr);
-    return copyPtr;
+    TclNewObj(copyObj);
+    TclInvalidateStringRep(copyObj);
+    DupListInternalRep(listObj, copyObj);
+    return copyObj;
 }
 
 /*
- *----------------------------------------------------------------------
+ *------------------------------------------------------------------------
  *
- * TclListObjRange --
+ * ListRepRange --
  *
- *	Makes a slice of a list value.
- *      *listPtr must be known to be a valid list.
+ *	Initializes a ListRep as a range within the passed ListRep.
+ *	The range limits are clamped to the list boundaries.
  *
  * Results:
- *	Returns a pointer to the sliced list.
- *      This may be a new object or the same object if not shared.
+ *	None.
  *
  * Side effects:
- *	The possible conversion of the object referenced by listPtr
- *	to a list object.
- *
- *----------------------------------------------------------------------
+ *      The ListStore and ListSpan referenced by in the returned ListRep
+ *      may or may not be the same as those passed in. For example, the
+ *      ListStore may differ because the range is small enough that a new
+ *      ListStore is more memory-optimal. The ListSpan may differ because
+ *      it is NULL or shared. Regardless, reference counts on the returned
+ *      values are not incremented. Generally, ListObjReplaceRepAndInvalidate
+ *      may be used to store the new ListRep back into an object or a
+ *      ListRepIncrRefs followed by ListRepDecrRefs to free in case of errors.
+ *	Any other use should be carefully reconsidered.
+ *      TODO WARNING:- this is an awkward interface and easy for caller
+ *      to get wrong. Mostly due to refcount combinations. Perhaps passing
+ *      in the source listObj instead of source listRep might simplify.
+ *
+ *------------------------------------------------------------------------
  */
-
-Tcl_Obj *
-TclListObjRange(
-    Tcl_Obj *listPtr,		/* List object to take a range from. */
-    int fromIdx,		/* Index of first element to include. */
-    int toIdx)			/* Index of last element to include. */
+static void
+ListRepRange(
+    ListRep *srcRepPtr,    /* Contains source of the range */
+    ListSizeT rangeStart,  /* Index of first element to include */
+    ListSizeT rangeEnd,    /* Index of last element to include */
+    int preserveSrcRep,    /* If true, srcRepPtr contents must not be
+			      modified (generally because a shared Tcl_Obj
+			      references it) */
+    ListRep *rangeRepPtr)  /* Output. Must NOT be == srcRepPtr */
 {
-    Tcl_Obj **elemPtrs;
-    int listLen, i, newLen;
-    List *listRepPtr;
-
-    TclListObjGetElementsM(NULL, listPtr, &listLen, &elemPtrs);
-
-    if (fromIdx < 0) {
-	fromIdx = 0;
+    Tcl_Obj **srcElems;
+    ListSizeT numSrcElems = ListRepLength(srcRepPtr);
+    ListSizeT rangeLen;
+    ListSizeT numAfterRangeEnd;
+
+    LISTREP_CHECK(srcRepPtr);
+
+    /* Take the opportunity to garbage collect */
+    /* TODO - we probably do not need the preserveSrcRep here unlike later */
+    if (!preserveSrcRep) {
+        /* T:listrep-1.{4,5,8,9},2.{4:7},3.{15:18},4.{7,8} */
+	ListRepFreeUnreferenced(srcRepPtr);
+    } /* else T:listrep-2.{4.2,4.3,5.2,5.3,6.2,7.2,8.1} */
+
+    if (rangeStart < 0) {
+	rangeStart = 0;
     }
-    if (toIdx >= listLen) {
-	toIdx = listLen-1;
+    if (rangeEnd >= numSrcElems) {
+	rangeEnd = numSrcElems - 1;
     }
-    if (fromIdx > toIdx) {
-	Tcl_Obj *obj;
-	TclNewObj(obj);
-	return obj;
-    }
-
-    newLen = toIdx - fromIdx + 1;
-
-    if (Tcl_IsShared(listPtr) ||
-	    ((ListRepPtr(listPtr)->refCount > 1))) {
-	return Tcl_NewListObj(newLen, &elemPtrs[fromIdx]);
+    if (rangeStart > rangeEnd) {
+	/* Empty list of capacity 1. */
+	ListRepInit(1, NULL, LISTREP_PANIC_ON_FAIL, rangeRepPtr);
+	return;
     }
 
-    /*
-     * In-place is possible.
-     */
+    rangeLen = rangeEnd - rangeStart + 1;
 
     /*
-     * Even if nothing below cause any changes, we still want the
-     * string-canonizing effect of [lrange 0 end].
+     * We can create a range one of four ways:
+     *  (0) Range encapsulates entire list
+     *  (1) Special case: deleting in-place from end of an unshared object
+     *  (2) Use a ListSpan referencing the current ListStore
+     *  (3) Creating a new ListStore
+     *  (4) Removing all elements outside the range in the current ListStore
+     * Option (4) may only be done if caller has not disallowed it AND
+     * the ListStore is not shared.
+     *
+     * The choice depends on heuristics related to speed and memory.
+     * TODO - heuristics below need to be measured and tuned.
+     *
+     * Note: Even if nothing below cause any changes, we still want the
+     * string-canonizing effect of [lrange 0 end] so the Tcl_Obj should not
+     * be returned as is even if the range encompasses the whole list.
      */
+    if (rangeStart == 0 && rangeEnd == (numSrcElems-1)) {
+	/* Option 0 - entire list. This may be used to canonicalize */
+        /* T:listrep-1.10.1,2.8.1 */
+	*rangeRepPtr = *srcRepPtr; /* Not ref counts not incremented */
+    } else if (rangeStart == 0 && (!preserveSrcRep)
+	       && (!ListRepIsShared(srcRepPtr) && srcRepPtr->spanPtr == NULL)) {
+	/* Option 1 - Special case unshared, exclude end elements, no span  */
+	LIST_ASSERT(srcRepPtr->storePtr->firstUsed == 0); /* If no span */
+	ListRepElements(srcRepPtr, numSrcElems, srcElems);
+	numAfterRangeEnd = numSrcElems - (rangeEnd + 1);
+	/* Assert: Because numSrcElems > rangeEnd earlier */
+	LIST_ASSERT(numAfterRangeEnd >= 0);
+	if (numAfterRangeEnd != 0) {
+            /* T:listrep-1.{8,9} */
+	    ObjArrayDecrRefs(srcElems, rangeEnd + 1, numAfterRangeEnd);
+	}
+	/* srcRepPtr->storePtr->firstUsed,numAllocated unchanged */
+	srcRepPtr->storePtr->numUsed = rangeLen;
+	srcRepPtr->storePtr->flags = 0;
+	rangeRepPtr->storePtr = srcRepPtr->storePtr; /* Note no incr ref */
+	rangeRepPtr->spanPtr = NULL;
+    } else if (ListSpanMerited(rangeLen,
+			       srcRepPtr->storePtr->numUsed,
+			       srcRepPtr->storePtr->numAllocated)) {
+	/* Option 2 - because span would be most efficient */
+	ListSizeT spanStart = ListRepStart(srcRepPtr) + rangeStart;
+	if (!preserveSrcRep && srcRepPtr->spanPtr
+	    && srcRepPtr->spanPtr->refCount <= 1) {
+	    /* If span is not shared reuse it */
+            /* T:listrep-2.7.3,3.{16,18} */
+	    srcRepPtr->spanPtr->spanStart = spanStart;
+	    srcRepPtr->spanPtr->spanLength = rangeLen;
+	    *rangeRepPtr = *srcRepPtr;
+	} else {
+	    /* Span not present or is shared. */
+            /* T:listrep-1.5,2.{5,7},4.{7,8} */
+	    rangeRepPtr->storePtr = srcRepPtr->storePtr;
+	    rangeRepPtr->spanPtr = ListSpanNew(spanStart, rangeLen);
+	}
+        /*
+         * We have potentially created a new internal representation that
+         * references the same storage as srcRep but not yet incremented its
+         * reference count. So do NOT call freezombies if preserveSrcRep
+         * is mandated.
+         */
+	if (!preserveSrcRep) {
+            /* T:listrep-1.{5.1,5.2,5.4},2.{5,7},3.{16,18},4.{7,8} */
+	    ListRepFreeUnreferenced(rangeRepPtr);
+	}
+    } else if (preserveSrcRep || ListRepIsShared(srcRepPtr)) {
+	/* Option 3 - span or modification in place not allowed/desired */
+        /* T:listrep-2.{4,6} */
+	ListRepElements(srcRepPtr, numSrcElems, srcElems);
+	/* TODO - allocate extra space? */
+	ListRepInit(rangeLen,
+		    &srcElems[rangeStart],
+		    LISTREP_PANIC_ON_FAIL,
+		    rangeRepPtr);
+    } else {
+	/*
+	 * Option 4 - modify in place. Note that because of the invariant
+	 * that spanless list stores must start at 0, we have to move
+	 * everything to the front.
+	 * TODO - perhaps if a span already exists, no need to move to front?
+	 * or maybe no need to move all the way to the front?
+	 * TODO - if range is small relative to allocation, allocate new?
+	 */
 
-    TclInvalidateStringRep(listPtr);
-
-    /*
-     * Delete elements that should not be included.
-     */
+	/* Asserts follow from call to ListRepFreeUnreferenced earlier */
+	LIST_ASSERT(!preserveSrcRep);
+	LIST_ASSERT(!ListRepIsShared(srcRepPtr));
+	LIST_ASSERT(ListRepStart(srcRepPtr) == srcRepPtr->storePtr->firstUsed);
+	LIST_ASSERT(ListRepLength(srcRepPtr) == srcRepPtr->storePtr->numUsed);
 
-    for (i = 0; i < fromIdx; i++) {
-	TclDecrRefCount(elemPtrs[i]);
-    }
-    for (i = toIdx + 1; i < listLen; i++) {
-	TclDecrRefCount(elemPtrs[i]);
-    }
+	ListRepElements(srcRepPtr, numSrcElems, srcElems);
 
-    if (fromIdx > 0) {
-	memmove(elemPtrs, &elemPtrs[fromIdx],
-		(size_t) newLen * sizeof(Tcl_Obj*));
+	/* Free leading elements outside range */
+	if (rangeStart != 0) {
+            /* T:listrep-1.4,3.15 */
+	    ObjArrayDecrRefs(srcElems, 0, rangeStart);
+	}
+	/* Ditto for trailing */
+	numAfterRangeEnd = numSrcElems - (rangeEnd + 1);
+	/* Assert: Because numSrcElems > rangeEnd earlier */
+	LIST_ASSERT(numAfterRangeEnd >= 0);
+	if (numAfterRangeEnd != 0) {
+            /* T:listrep-3.17 */
+	    ObjArrayDecrRefs(srcElems, rangeEnd + 1, numAfterRangeEnd);
+	}
+	memmove(&srcRepPtr->storePtr->slots[0],
+		&srcRepPtr->storePtr
+		     ->slots[srcRepPtr->storePtr->firstUsed + rangeStart],
+		rangeLen * sizeof(Tcl_Obj *));
+	srcRepPtr->storePtr->firstUsed = 0;
+	srcRepPtr->storePtr->numUsed = rangeLen;
+	srcRepPtr->storePtr->flags = 0;
+	if (srcRepPtr->spanPtr) {
+	    /* In case the source has a span, update it for consistency */
+            /* T:listrep-3.{15,17} */
+	    srcRepPtr->spanPtr->spanStart = srcRepPtr->storePtr->firstUsed;
+	    srcRepPtr->spanPtr->spanLength = srcRepPtr->storePtr->numUsed;
+	}
+	rangeRepPtr->storePtr = srcRepPtr->storePtr;
+	rangeRepPtr->spanPtr = NULL;
     }
 
-    listRepPtr = ListRepPtr(listPtr);
-    listRepPtr->elemCount = newLen;
+    /* TODO - call freezombies here if !preserveSrcRep? */
 
-    return listPtr;
+    /* Note ref counts intentionally not incremented */
+    LISTREP_CHECK(rangeRepPtr);
+    return;
 }
 
 /*
  *----------------------------------------------------------------------
  *
- * Tcl_ListObjGetElements --
- *
- *	Retreive the elements in a list 'Tcl_Obj'.
+ * TclListObjRange --
  *
- * Value
+ *	Makes a slice of a list value.
+ *      *listObj must be known to be a valid list.
  *
- *	TCL_OK
+ * Results:
+ *	Returns a pointer to the sliced list.
+ *      This may be a new object or the same object if not shared.
+ *	Returns NULL if passed listObj was not a list and could not be
+ *	converted to one.
  *
- *	    A count of list elements is stored, 'objcPtr', And a pointer to the
- *	    array of elements in the list is stored in 'objvPtr'.
+ * Side effects:
+ *	The possible conversion of the object referenced by listPtr
+ *	to a list object.
  *
- *	    The elements accessible via 'objvPtr' should be treated as readonly
- *	    and the refCount for each object is _not_ incremented; the caller
- *	    must do that if it holds on to a reference. Furthermore, the
- *	    pointer and length returned by this function may change as soon as
- *	    any function is called on the list object. Be careful about
- *	    retaining the pointer in a local data structure.
+ *----------------------------------------------------------------------
+ */
+
+Tcl_Obj *
+TclListObjRange(
+    Tcl_Obj *listObj,		/* List object to take a range from. */
+    ListSizeT rangeStart,	/* Index of first element to include. */
+    ListSizeT rangeEnd)		/* Index of last element to include. */
+{
+    ListRep listRep;
+    ListRep resultRep;
+
+    int isShared;
+    if (TclListObjGetRep(NULL, listObj, &listRep) != TCL_OK)
+	return NULL;
+
+    isShared = Tcl_IsShared(listObj);
+
+    ListRepRange(&listRep, rangeStart, rangeEnd, isShared, &resultRep);
+
+    if (isShared) {
+        /* T:listrep-1.10.1,2.{4.2,4.3,5.2,5.3,6.2,7.2,8.1} */
+	TclNewObj(listObj);
+    } /* T:listrep-1.{4.3,5.1,5.2} */
+    ListObjReplaceRepAndInvalidate(listObj, &resultRep);
+    return listObj;
+}
+
+/*
+ *----------------------------------------------------------------------
  *
- *	TCL_ERROR
+ * Tcl_ListObjGetElements --
  *
- *	    'listPtr' is not a valid list. An error message is left in the
- *	    interpreter's result if 'interp' is not NULL.
+ *	This function returns an (objc,objv) array of the elements in a list
+ *	object.
  *
- * Effect
+ * Results:
+ *	The return value is normally TCL_OK; in this case *objcPtr is set to
+ *	the count of list elements and *objvPtr is set to a pointer to an
+ *	array of (*objcPtr) pointers to each list element. If listPtr does not
+ *	refer to a list object and the object can not be converted to one,
+ *	TCL_ERROR is returned and an error message will be left in the
+ *	interpreter's result if interp is not NULL.
+ *
+ *	The objects referenced by the returned array should be treated as
+ *	readonly and their ref counts are _not_ incremented; the caller must
+ *	do that if it holds on to a reference. Furthermore, the pointer and
+ *	length returned by this function may change as soon as any function is
+ *	called on the list object; be careful about retaining the pointer in a
+ *	local data structure.
  *
- *	'listPtr' is converted to a list object if it isn't one already.
+ * Side effects:
+ *	The possible conversion of the object referenced by listPtr
+ *	to a list object.
  *
  *----------------------------------------------------------------------
  */
@@ -525,35 +1654,18 @@ TclListObjRange(
 int
 Tcl_ListObjGetElements(
     Tcl_Interp *interp,		/* Used to report errors if not NULL. */
-    Tcl_Obj *listPtr,	/* List object for which an element array is
+    Tcl_Obj *objPtr,		/* List object for which an element array is
 				 * to be returned. */
-    int *objcPtr,		/* Where to store the count of objects
+    ListSizeT *objcPtr,		/* Where to store the count of objects
 				 * referenced by objv. */
     Tcl_Obj ***objvPtr)		/* Where to store the pointer to an array of
 				 * pointers to the list's objects. */
 {
-    List *listRepPtr;
+    ListRep listRep;
 
-    ListGetInternalRep(listPtr, listRepPtr);
-
-    if (listRepPtr == NULL) {
-	int result;
-	int length;
-
-	(void) Tcl_GetStringFromObj(listPtr, &length);
-	if (length == 0) {
-	    *objcPtr = 0;
-	    *objvPtr = NULL;
-	    return TCL_OK;
-	}
-	result = SetListFromAny(interp, listPtr);
-	if (result != TCL_OK) {
-	    return result;
-	}
-	ListGetInternalRep(listPtr, listRepPtr);
-    }
-    *objcPtr = listRepPtr->elemCount;
-    *objvPtr = listRepPtr->elements;
+    if (TclListObjGetRep(interp, objPtr, &listRep) != TCL_OK)
+	return TCL_ERROR;
+    ListRepElements(&listRep, *objcPtr, *objvPtr);
     return TCL_OK;
 }
 
@@ -562,49 +1674,37 @@ Tcl_ListObjGetElements(
  *
  * Tcl_ListObjAppendList --
  *
- *	Appends the elements of elemListPtr to those of listPtr.
- *
- * Value
- *
- *	TCL_OK
+ *	This function appends the elements in the list fromObj
+ *	to toObj. toObj must not be shared else the function will panic.
  *
- *	    Success.
- *
- *	TCL_ERROR
- *
- *	    'listPtr' or 'elemListPtr' are not valid lists.  An error
- *	    message is left in the interpreter's result if 'interp' is not NULL.
- *
- * Effect
+ * Results:
+ *	The return value is normally TCL_OK. If fromObj or toObj do not
+ *	refer to list values, TCL_ERROR is returned and an error message is
+ *	left in the interpreter's result if interp is not NULL.
  *
- *	The reference count of each element of 'elemListPtr' as it is added to
- *	'listPtr'. 'listPtr' and 'elemListPtr' are converted to 'tclListType'
- *	if they are not already. Appending the new elements may cause the
- *	array of element pointers in 'listObj' to grow.  If any objects are
- *	appended to 'listPtr'. Any preexisting string representation of
- *	'listPtr' is invalidated.
+ * Side effects:
+ *	The reference counts of the elements in fromObj are incremented
+ *	since the list now refers to them. toObj and fromObj are
+ *	converted, if necessary, to list objects. Also, appending the new
+ *	elements may cause toObj's array of element pointers to grow.
+ *	toObj's old string representation, if any, is invalidated.
  *
  *----------------------------------------------------------------------
  */
-
 int
 Tcl_ListObjAppendList(
     Tcl_Interp *interp,		/* Used to report errors if not NULL. */
-    Tcl_Obj *listPtr,	/* List object to append elements to. */
-    Tcl_Obj *elemListPtr)	/* List obj with elements to append. */
+    Tcl_Obj *toObj,		/* List object to append elements to. */
+    Tcl_Obj *fromObj)		/* List obj with elements to append. */
 {
-    int objc;
+    ListSizeT objc;
     Tcl_Obj **objv;
 
-    if (Tcl_IsShared(listPtr)) {
+    if (Tcl_IsShared(toObj)) {
 	Tcl_Panic("%s called with shared object", "Tcl_ListObjAppendList");
     }
 
-    /*
-     * Pull the elements to append from elemListPtr.
-     */
-
-    if (TCL_OK != TclListObjGetElementsM(interp, elemListPtr, &objc, &objv)) {
+    if (TclListObjGetElementsM(interp, fromObj, &objc, &objv) != TCL_OK) {
 	return TCL_ERROR;
     }
 
@@ -613,249 +1713,246 @@ Tcl_ListObjAppendList(
      * Delete zero existing elements.
      */
 
-    return Tcl_ListObjReplace(interp, listPtr, LIST_MAX, 0, objc, objv);
+    return TclListObjAppendElements(interp, toObj, objc, objv);
 }
 
 /*
- *----------------------------------------------------------------------
- *
- * Tcl_ListObjAppendElement --
- *
- *	Like 'Tcl_ListObjAppendList', but Appends a single value to a list.
- *
- * Value
- *
- *	TCL_OK
+ *------------------------------------------------------------------------
  *
- *	    'objPtr' is appended to the elements of 'listPtr'.
+ * TclListObjAppendElements --
  *
- *	TCL_ERROR
+ *      Appends multiple elements to a Tcl_Obj list object. If
+ *      the passed Tcl_Obj is not a list object, it will be converted to one
+ *      and an error raised if the conversion fails.
  *
- *	    listPtr does not refer to a list object and the object can not be
- *	    converted to one. An error message will be left in the
- *	    interpreter's result if interp is not NULL.
+ * 	The Tcl_Obj must not be shared though the internal representation
+ * 	may be.
  *
- * Effect
+ * Results:
+ *	On success, TCL_OK is returned with the specified elements appended.
+ *	On failure, TCL_ERROR is returned with an error message in the
+ *	interpreter if not NULL.
  *
- *	If 'listPtr' is not already of type 'tclListType', it is converted.
- *	The 'refCount' of 'objPtr' is incremented as it is added to 'listPtr'.
- *	Appending the new element may cause the the array of element pointers
- *	in 'listObj' to grow.  Any preexisting string representation of
- *	'listPtr' is invalidated.
+ * Side effects:
+ *    None.
  *
- *----------------------------------------------------------------------
+ *------------------------------------------------------------------------
  */
-
-int
-Tcl_ListObjAppendElement(
+ int TclListObjAppendElements (
     Tcl_Interp *interp,		/* Used to report errors if not NULL. */
-    Tcl_Obj *listPtr,		/* List object to append objPtr to. */
-    Tcl_Obj *objPtr)		/* Object to append to listPtr's list. */
+    Tcl_Obj *toObj,		/* List object to append */
+    ListSizeT elemCount,        /* Number of elements in elemObjs[] */
+    Tcl_Obj * const elemObjv[])	/* Objects to append to toObj's list. */
 {
-    List *listRepPtr, *newPtr = NULL;
-    int numElems, numRequired;
-    int needGrow, isShared, attempt;
+    ListRep listRep;
+    Tcl_Obj **toObjv;
+    ListSizeT toLen;
+    ListSizeT finalLen;
 
-    if (Tcl_IsShared(listPtr)) {
-	Tcl_Panic("%s called with shared object", "Tcl_ListObjAppendElement");
+    if (Tcl_IsShared(toObj)) {
+	Tcl_Panic("%s called with shared object", "TclListObjAppendElements");
     }
 
-    ListGetInternalRep(listPtr, listRepPtr);
-    if (listRepPtr == NULL) {
-	int result;
-	int length;
+    if (TclListObjGetRep(interp, toObj, &listRep) != TCL_OK)
+	return TCL_ERROR; /* Cannot be converted to a list */
 
-	(void) Tcl_GetStringFromObj(listPtr, &length);
-	if (length == 0) {
-	    Tcl_SetListObj(listPtr, 1, &objPtr);
-	    return TCL_OK;
-	}
-	result = SetListFromAny(interp, listPtr);
-	if (result != TCL_OK) {
-	    return result;
-	}
-	ListGetInternalRep(listPtr, listRepPtr);
-    }
-
-    numElems = listRepPtr->elemCount;
-    numRequired = numElems + 1 ;
-    needGrow = (numRequired > listRepPtr->maxElemCount);
-    isShared = (listRepPtr->refCount > 1);
+    if (elemCount == 0)
+	return TCL_OK; /* Nothing to do. Note AFTER check for list above */
 
-    if (numRequired > LIST_MAX) {
-	if (interp != NULL) {
-	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
-		    "max length of a Tcl list (%d elements) exceeded",
-		    LIST_MAX));
-	    Tcl_SetErrorCode(interp, "TCL", "MEMORY", NULL);
-	}
-	return TCL_ERROR;
+    ListRepElements(&listRep, toLen, toObjv);
+    if (elemCount > LIST_MAX || toLen > (LIST_MAX - elemCount)) {
+	return ListLimitExceededError(interp);
     }
 
-    if (needGrow && !isShared) {
+    finalLen = toLen + elemCount;
+    if (!ListRepIsShared(&listRep)) {
 	/*
-	 * Need to grow + unshared internalrep => try to realloc
+	 * Reuse storage if possible. Even if too small, realloc-ing instead
+	 * of creating a new ListStore will save us on manipulating Tcl_Obj
+	 * reference counts on the elements which is a substantial cost
+	 * if the list is not small.
 	 */
+	ListSizeT numTailFree;
 
-	attempt = 2 * numRequired;
-	if (attempt <= LIST_MAX) {
-	    newPtr = (List *)attemptckrealloc(listRepPtr, LIST_SIZE(attempt));
-	}
-	if (newPtr == NULL) {
-	    attempt = numRequired + 1 + TCL_MIN_ELEMENT_GROWTH;
-	    if (attempt > LIST_MAX) {
-		attempt = LIST_MAX;
-	    }
-	    newPtr = (List *)attemptckrealloc(listRepPtr, LIST_SIZE(attempt));
-	}
-	if (newPtr == NULL) {
-	    attempt = numRequired;
-	    newPtr = (List *)attemptckrealloc(listRepPtr, LIST_SIZE(attempt));
-	}
-	if (newPtr) {
-	    listRepPtr = newPtr;
-	    listRepPtr->maxElemCount = attempt;
-	    needGrow = 0;
-	}
-    }
-    if (isShared || needGrow) {
-	Tcl_Obj **dst, **src = listRepPtr->elements;
-
-	/*
-	 * Either we have a shared internalrep and we must copy to write, or we
-	 * need to grow and realloc attempts failed.  Attempt internalrep copy.
-	 */
-
-	attempt = 2 * numRequired;
-	newPtr = AttemptNewList(NULL, attempt, NULL);
-	if (newPtr == NULL) {
-	    attempt = numRequired + 1 + TCL_MIN_ELEMENT_GROWTH;
-	    if (attempt > LIST_MAX) {
-		attempt = LIST_MAX;
-	    }
-	    newPtr = AttemptNewList(NULL, attempt, NULL);
-	}
-	if (newPtr == NULL) {
-	    attempt = numRequired;
-	    newPtr = AttemptNewList(interp, attempt, NULL);
-	}
-	if (newPtr == NULL) {
-	    /*
-	     * All growth attempts failed; throw the error.
-	     */
-
-	    return TCL_ERROR;
-	}
+	ListRepFreeUnreferenced(&listRep); /* Collect garbage before checking room */
 
-	dst = newPtr->elements;
-	newPtr->refCount++;
-	newPtr->canonicalFlag = listRepPtr->canonicalFlag;
-	newPtr->elemCount = listRepPtr->elemCount;
+	LIST_ASSERT(ListRepStart(&listRep) == listRep.storePtr->firstUsed);
+	LIST_ASSERT(ListRepLength(&listRep) == listRep.storePtr->numUsed);
+	LIST_ASSERT(toLen == listRep.storePtr->numUsed);
 
-	if (isShared) {
-	    /*
-	     * The original internalrep must remain undisturbed.  Copy into the new
-	     * one and bump refcounts
-	     */
-	    while (numElems--) {
-		*dst = *src++;
-		Tcl_IncrRefCount(*dst++);
+	if (finalLen > listRep.storePtr->numAllocated) {
+	    /* T:listrep-1.{2,11},3.6 */
+	    ListStore *newStorePtr;
+	    newStorePtr = ListStoreReallocate(listRep.storePtr, finalLen);
+	    if (newStorePtr == NULL) {
+		return MemoryAllocationError(interp, LIST_SIZE(finalLen));
 	    }
-	    listRepPtr->refCount--;
-	} else {
+	    LIST_ASSERT(newStorePtr->numAllocated >= finalLen);
+	    listRep.storePtr = newStorePtr;
 	    /*
-	     * Old internalrep to be freed, re-use refCounts.
+	     * WARNING: at this point the Tcl_Obj internal rep potentially
+	     * points to freed storage if the reallocation returned a
+	     * different location. Overwrite it to bring it back in sync.
 	     */
-
-	    memcpy(dst, src, numElems * sizeof(Tcl_Obj *));
-	    ckfree(listRepPtr);
-	}
-	listRepPtr = newPtr;
+	    ListObjStompRep(toObj, &listRep);
+	} /* else T:listrep-3.{4,5} */
+	LIST_ASSERT(listRep.storePtr->numAllocated >= finalLen);
+	/* Current store big enough */
+	numTailFree = ListRepNumFreeTail(&listRep);
+	LIST_ASSERT((numTailFree + listRep.storePtr->firstUsed)
+		    >= elemCount); /* Total free */
+	if (numTailFree < elemCount) {
+	    /* Not enough room at back. Move some to front */
+            /* T:listrep-3.5 */
+	    ListSizeT shiftCount = elemCount - numTailFree;
+	    /* Divide remaining space between front and back */
+	    shiftCount += (listRep.storePtr->numAllocated - finalLen) / 2;
+	    LIST_ASSERT(shiftCount <= listRep.storePtr->firstUsed);
+	    if (shiftCount) {
+                /* T:listrep-3.5 */
+		ListRepUnsharedShiftDown(&listRep, shiftCount);
+            }
+	} /* else T:listrep-3.{4,6} */
+	ObjArrayCopy(&listRep.storePtr->slots[ListRepStart(&listRep)
+					      + ListRepLength(&listRep)],
+		     elemCount,
+		     elemObjv);
+	listRep.storePtr->numUsed = finalLen;
+	if (listRep.spanPtr) {
+            /* T:listrep-3.{4,5,6} */
+	    LIST_ASSERT(listRep.spanPtr->spanStart
+			== listRep.storePtr->firstUsed);
+	    listRep.spanPtr->spanLength = finalLen;
+	} /* else T:listrep-3.6.3 */
+	LIST_ASSERT(ListRepStart(&listRep) == listRep.storePtr->firstUsed);
+	LIST_ASSERT(ListRepLength(&listRep) == finalLen);
+	LISTREP_CHECK(&listRep);
+
+	ListObjReplaceRepAndInvalidate(toObj, &listRep);
+	return TCL_OK;
     }
-    ListResetInternalRep(listPtr, listRepPtr);
-    listRepPtr->refCount++;
-    TclFreeInternalRep(listPtr);
-    ListSetInternalRep(listPtr, listRepPtr);
-    listRepPtr->refCount--;
-
-    /*
-     * Add objPtr to the end of listPtr's array of element pointers. Increment
-     * the ref count for the (now shared) objPtr.
-     */
-
-    listRepPtr->elements[listRepPtr->elemCount] = objPtr;
-    Tcl_IncrRefCount(objPtr);
-    listRepPtr->elemCount++;
 
     /*
-     * Invalidate any old string representation since the list's internal
-     * representation has changed.
+     * Have to make a new list rep, either shared or no room in old one.
+     * If the old list did not have a span (all elements at front), do
+     * not leave space in the front either, assuming all appends and no
+     * prepends.
      */
+    if (ListRepInit(finalLen,
+		    NULL,
+		    listRep.spanPtr ? LISTREP_SPACE_FAVOR_BACK
+				    : LISTREP_SPACE_ONLY_BACK,
+		    &listRep)
+	!= TCL_OK) {
+	return TCL_ERROR;
+    }
+    LIST_ASSERT(listRep.storePtr->numAllocated >= finalLen);
 
-    TclInvalidateStringRep(listPtr);
+    if (toLen) {
+        /* T:listrep-2.{2,9},4.5 */
+	ObjArrayCopy(ListRepSlotPtr(&listRep, 0), toLen, toObjv);
+    }
+    ObjArrayCopy(ListRepSlotPtr(&listRep, toLen), elemCount, elemObjv);
+    listRep.storePtr->numUsed = finalLen;
+    if (listRep.spanPtr) {
+        /* T:listrep-4.5 */
+	LIST_ASSERT(listRep.spanPtr->spanStart == listRep.storePtr->firstUsed);
+	listRep.spanPtr->spanLength = finalLen;
+    }
+    LISTREP_CHECK(&listRep);
+    ListObjReplaceRepAndInvalidate(toObj, &listRep);
     return TCL_OK;
 }
 
 /*
  *----------------------------------------------------------------------
  *
- * Tcl_ListObjIndex --
+ * Tcl_ListObjAppendElement --
  *
- * 	Retrieve a pointer to the element of 'listPtr' at 'index'.  The index
- * 	of the first element is 0.
+ *	This function is a special purpose version of Tcl_ListObjAppendList:
+ *	it appends a single object referenced by elemObj to the list object
+ *	referenced by toObj. If toObj is not already a list object, an
+ *	attempt will be made to convert it to one.
  *
- * Value
+ * Results:
+ *	The return value is normally TCL_OK; in this case elemObj is added to
+ *	the end of toObj's list. If toObj does not refer to a list object
+ *	and the object can not be converted to one, TCL_ERROR is returned and
+ *	an error message will be left in the interpreter's result if interp is
+ *	not NULL.
  *
- * 	TCL_OK
+ * Side effects:
+ *	The ref count of elemObj is incremented since the list now refers to
+ *	it. toObj will be converted, if necessary, to a list object. Also,
+ *	appending the new element may cause listObj's array of element
+ *	pointers to grow. toObj's old string representation, if any, is
+ *	invalidated.
  *
- *	    A pointer to the element at 'index' is stored in 'objPtrPtr'.  If
- *	    'index' is out of range, NULL is stored in 'objPtrPtr'.  This
- *	    object should be treated as readonly and its 'refCount' is _not_
- *	    incremented. The caller must do that if it holds on to the
- *	    reference.
+ *----------------------------------------------------------------------
+ */
+int
+Tcl_ListObjAppendElement(
+    Tcl_Interp *interp,		/* Used to report errors if not NULL. */
+    Tcl_Obj *toObj,		/* List object to append elemObj to. */
+    Tcl_Obj *elemObj)		/* Object to append to toObj's list. */
+{
+    /*
+     * TODO - compare perf with 8.6 to see if worth optimizing single
+     * element case
+     */
+    return TclListObjAppendElements(interp, toObj, 1, &elemObj);
+}
+
+/*
+ *----------------------------------------------------------------------
  *
- * 	TCL_ERROR
+ * Tcl_ListObjIndex --
  *
- * 	    'listPtr' is not a valid list. An an error message is left in the
- * 	    interpreter's result if 'interp' is not NULL.
+ *	This function returns a pointer to the index'th object from the list
+ *	referenced by listPtr. The first element has index 0. If index is
+ *	negative or greater than or equal to the number of elements in the
+ *	list, a NULL is returned. If listPtr is not a list object, an attempt
+ *	will be made to convert it to a list.
  *
- *  Effect
+ * Results:
+ *	The return value is normally TCL_OK; in this case objPtrPtr is set to
+ *	the Tcl_Obj pointer for the index'th list element or NULL if index is
+ *	out of range. This object should be treated as readonly and its ref
+ *	count is _not_ incremented; the caller must do that if it holds on to
+ *	the reference. If listPtr does not refer to a list and can't be
+ *	converted to one, TCL_ERROR is returned and an error message is left
+ *	in the interpreter's result if interp is not NULL.
  *
- * 	If 'listPtr' is not already of type 'tclListType', it is converted.
+ * Side effects:
+ *	listPtr will be converted, if necessary, to a list object.
  *
  *----------------------------------------------------------------------
  */
-
 int
 Tcl_ListObjIndex(
-    Tcl_Interp *interp,		/* Used to report errors if not NULL. */
-    Tcl_Obj *listPtr,	/* List object to index into. */
-    int index,		/* Index of element to return. */
-    Tcl_Obj **objPtrPtr)	/* The resulting Tcl_Obj* is stored here. */
+    Tcl_Interp *interp,  /* Used to report errors if not NULL. */
+    Tcl_Obj *listObj,    /* List object to index into. */
+    ListSizeT index,           /* Index of element to return. */
+    Tcl_Obj **objPtrPtr) /* The resulting Tcl_Obj* is stored here. */
 {
-    List *listRepPtr;
-
-    ListGetInternalRep(listPtr, listRepPtr);
-    if (listRepPtr == NULL) {
-	int result;
-	int length;
+    Tcl_Obj **elemObjs;
+    ListSizeT numElems;
 
-	(void) Tcl_GetStringFromObj(listPtr, &length);
-	if (length == 0) {
-	    *objPtrPtr = NULL;
-	    return TCL_OK;
-	}
-	result = SetListFromAny(interp, listPtr);
-	if (result != TCL_OK) {
-	    return result;
-	}
-	ListGetInternalRep(listPtr, listRepPtr);
+    /*
+     * TODO
+     * Unlike the original list code, this does not optimize for lindex'ing
+     * an empty string when the internal rep is not already a list. On the
+     * other hand, this code will be faster for the case where the object
+     * is currently a dict. Benchmark the two cases.
+     */
+    if (TclListObjGetElementsM(interp, listObj, &numElems, &elemObjs)
+	!= TCL_OK) {
+	return TCL_ERROR;
     }
-
-    if ((index < 0) || (index >= listRepPtr->elemCount)) {
+    if ((index < 0) || (index >= numElems)) {
 	*objPtrPtr = NULL;
     } else {
-	*objPtrPtr = listRepPtr->elements[index];
+	*objPtrPtr = elemObjs[index];
     }
 
     return TCL_OK;
@@ -866,20 +1963,19 @@ Tcl_ListObjIndex(
  *
  * Tcl_ListObjLength --
  *
- * 	Retrieve the number of elements in a list.
- *
- * Value
+ *	This function returns the number of elements in a list object. If the
+ *	object is not already a list object, an attempt will be made to
+ *	convert it to one.
  *
- *	TCL_OK
- *
- *	    A count of list elements is stored at the address provided by
- *	    'intPtr'. If 'listPtr' is not already of type 'tclListPtr', it is
- *	    converted.
- *
- *	TCL_ERROR
+ * Results:
+ *	The return value is normally TCL_OK; in this case *intPtr will be set
+ *	to the integer count of list elements. If listPtr does not refer to a
+ *	list object and the object can not be converted to one, TCL_ERROR is
+ *	returned and an error message will be left in the interpreter's result
+ *	if interp is not NULL.
  *
- *	    'listPtr' is not a valid list.  An error message will be left in
- *	    the interpreter's result if 'interp' is not NULL.
+ * Side effects:
+ *	The possible conversion of the argument object to a list object.
  *
  *----------------------------------------------------------------------
  */
@@ -887,30 +1983,23 @@ Tcl_ListObjIndex(
 #undef Tcl_ListObjLength
 int
 Tcl_ListObjLength(
-    Tcl_Interp *interp,		/* Used to report errors if not NULL. */
-    Tcl_Obj *listPtr,	/* List object whose #elements to return. */
-    int *intPtr)	/* The resulting length is stored here. */
+    Tcl_Interp *interp,	/* Used to report errors if not NULL. */
+    Tcl_Obj *listObj,	/* List object whose #elements to return. */
+    ListSizeT *lenPtr)	/* The resulting int is stored here. */
 {
-    List *listRepPtr;
-
-    ListGetInternalRep(listPtr, listRepPtr);
-    if (listRepPtr == NULL) {
-	int result;
-	int length;
+    ListRep listRep;
 
-	(void) Tcl_GetStringFromObj(listPtr, &length);
-	if (length == 0) {
-	    *intPtr = 0;
-	    return TCL_OK;
-	}
-	result = SetListFromAny(interp, listPtr);
-	if (result != TCL_OK) {
-	    return result;
-	}
-	ListGetInternalRep(listPtr, listRepPtr);
+    /*
+     * TODO
+     * Unlike the original list code, this does not optimize for lindex'ing
+     * an empty string when the internal rep is not already a list. On the
+     * other hand, this code will be faster for the case where the object
+     * is currently a dict. Benchmark the two cases.
+     */
+    if (TclListObjGetRep(interp, listObj, &listRep) != TCL_OK) {
+	return TCL_ERROR;
     }
-
-    *intPtr = listRepPtr->elemCount;
+    *lenPtr = ListRepLength(&listRep);
     return TCL_OK;
 }
 
@@ -919,296 +2008,498 @@ Tcl_ListObjLength(
  *
  * Tcl_ListObjReplace --
  *
- *	Replace values in a list.
- *
- *	If 'first' is zero or TCL_INDEX_NONE, it refers to the first element. If
- *	'first' outside the range of elements in the list, no elements are
- *	deleted.
+ *	This function replaces zero or more elements of the list referenced by
+ *	listObj with the objects from an (objc,objv) array. The objc elements
+ *	of the array referenced by objv replace the count elements in listPtr
+ *	starting at first.
  *
- *	If 'count' is zero or TCL_INDEX_NONE no elements are deleted, and any new
- *	elements are inserted at the beginning of the list.
+ *	If the argument first is zero or negative, it refers to the first
+ *	element. If first is greater than or equal to the number of elements
+ *	in the list, then no elements are deleted; the new elements are
+ *	appended to the list. Count gives the number of elements to replace.
+ *	If count is zero or negative then no elements are deleted; the new
+ *	elements are simply inserted before first.
  *
- * Value
+ *	The argument objv refers to an array of objc pointers to the new
+ *	elements to be added to listPtr in place of those that were deleted.
+ *	If objv is NULL, no new elements are added. If listPtr is not a list
+ *	object, an attempt will be made to convert it to one.
  *
- *	TCL_OK
- *
- *	    The first 'objc' values of 'objv' replaced 'count' elements in 'listPtr'
- *	    starting at 'first'.  If 'objc' 0, no new elements are added.
- *
- *	TCL_ERROR
- *
- *	    'listPtr' is not a valid list.   An error message is left in the
- *	    interpreter's result if 'interp' is not NULL.
- *
- * Effect
- *
- *	If 'listPtr' is not of type 'tclListType', it is converted if possible.
- *
- *	The 'refCount' of each element appended to the list is incremented.
- *	Similarly, the 'refCount' for each replaced element is decremented.
+ * Results:
+ *	The return value is normally TCL_OK. If listPtr does not refer to a
+ *	list object and can not be converted to one, TCL_ERROR is returned and
+ *	an error message will be left in the interpreter's result if interp is
+ *	not NULL.
  *
- *	If 'listPtr' is modified, any previous string representation is
- *	invalidated.
+ * Side effects:
+ *	The ref counts of the objc elements in objv are incremented since the
+ *	resulting list now refers to them. Similarly, the ref counts for
+ *	replaced objects are decremented. listObj is converted, if necessary,
+ *	to a list object. listObj's old string representation, if any, is
+ *	freed.
  *
  *----------------------------------------------------------------------
  */
-
 int
 Tcl_ListObjReplace(
     Tcl_Interp *interp,		/* Used for error reporting if not NULL. */
-    Tcl_Obj *listPtr,		/* List object whose elements to replace. */
-    int first,			/* Index of first element to replace. */
-    int count,			/* Number of elements to replace. */
-    int objc,			/* Number of objects to insert. */
-    Tcl_Obj *const objv[])	/* An array of objc pointers to Tcl objects to
-				 * insert. */
+    Tcl_Obj *listObj,		/* List object whose elements to replace. */
+    ListSizeT first,		/* Index of first element to replace. */
+    ListSizeT numToDelete,	/* Number of elements to replace. */
+    ListSizeT numToInsert,	/* Number of objects to insert. */
+    Tcl_Obj *const insertObjs[])/* Tcl objects to insert */
 {
-    List *listRepPtr;
-    Tcl_Obj **elemPtrs;
-    int numElems, numRequired, numAfterLast, start, i, j;
-    int needGrow, isShared;
-
-    if (Tcl_IsShared(listPtr)) {
+    ListRep listRep;
+    ListSizeT origListLen;
+    int lenChange;
+    int leadSegmentLen;
+    int tailSegmentLen;
+    ListSizeT numFreeSlots;
+    int leadShift;
+    int tailShift;
+    Tcl_Obj **listObjs;
+    int favor;
+
+    if (Tcl_IsShared(listObj)) {
 	Tcl_Panic("%s called with shared object", "Tcl_ListObjReplace");
     }
 
-    ListGetInternalRep(listPtr, listRepPtr);
-    if (listRepPtr == NULL) {
-	int length;
+    if (TclListObjGetRep(interp, listObj, &listRep) != TCL_OK)
+	return TCL_ERROR; /* Cannot be converted to a list */
 
-	(void) Tcl_GetStringFromObj(listPtr, &length);
-	if (length == 0) {
-	    if (objc == 0) {
-		return TCL_OK;
-	    }
-	    Tcl_SetListObj(listPtr, objc, NULL);
-	} else {
-	    int result = SetListFromAny(interp, listPtr);
+    /* TODO - will need modification if Tcl9 sticks to unsigned indices */
 
-	    if (result != TCL_OK) {
-		return result;
-	    }
-	}
-	ListGetInternalRep(listPtr, listRepPtr);
+    /* Make limits sane */
+    origListLen = ListRepLength(&listRep);
+    if (first < 0) {
+	first = 0;
+    }
+    if (first > origListLen) {
+	first = origListLen;	/* So we'll insert after last element. */
+    }
+    if (numToDelete < 0) {
+	numToDelete = 0;
+    } else if (first > ListSizeT_MAX - numToDelete /* Handle integer overflow */
+             || origListLen < first + numToDelete) {
+	numToDelete = origListLen - first;
+    }
+
+    if (numToInsert > ListSizeT_MAX - (origListLen - numToDelete)) {
+	return ListLimitExceededError(interp);
+    }
+
+    if ((first+numToDelete) >= origListLen) {
+	/* Operating at back of list. Favor leaving space at back */
+	favor = LISTREP_SPACE_FAVOR_BACK;
+    } else if (first == 0) {
+	/* Operating on front of list. Favor leaving space in front */
+	favor = LISTREP_SPACE_FAVOR_FRONT;
+    } else {
+	/* Operating on middle of list. */
+	favor = LISTREP_SPACE_FAVOR_NONE;
     }
 
     /*
-     * Note that when count == 0 and objc == 0, this routine is logically a
-     * no-op, removing and adding no elements to the list. However, by flowing
-     * through this routine anyway, we get the important side effect that the
-     * resulting listPtr is a list in canoncial form. This is important.
-     * Resist any temptation to optimize this case.
+     * There are a number of special cases to consider from an optimization
+     * point of view.
+     * (1) Pure deletes (numToInsert==0) from the front or back can be treated
+     * as a range op irrespective of whether the ListStore is shared or not
+     * (2) Pure inserts (numToDelete == 0)
+     *   (2a) Pure inserts at the back can be treated as appends
+     *   (2b) Pure inserts from the *front* can be optimized under certain
+     *   conditions by inserting before first ListStore slot in use if there
+     *   is room, again irrespective of sharing
+     * (3) If the ListStore is shared OR there is insufficient free space
+     * OR existing allocation is too large compared to new size, create
+     * a new ListStore
+     * (4) Unshared ListStore with sufficient free space. Delete, shift and
+     * insert within the ListStore.
      */
 
-    elemPtrs = listRepPtr->elements;
-    numElems = listRepPtr->elemCount;
+    /* Note: do not do TclInvalidateStringRep as yet in case there are errors */
 
-    if (first < 0) {
-	first = 0;
-    }
-    if (first >= numElems) {
-	first = numElems;	/* So we'll insert after last element. */
+    /* Check Case (1) - Treat pure deletes from front or back as range ops */
+    if (numToInsert == 0) {
+	if (numToDelete == 0) {
+	    /*
+             * Should force canonical even for no-op. Remember Tcl_Obj unshared
+             * so OK to invalidate string rep
+             */
+            /* T:listrep-1.10,2.8 */
+	    TclInvalidateStringRep(listObj);
+	    return TCL_OK;
+	}
+	if (first == 0) {
+	    /* Delete from front, so return tail. */
+            /* T:listrep-1.{4,5},2.{4,5},3.{15,16},4.7 */
+	    ListRep tailRep;
+	    ListRepRange(&listRep, numToDelete, origListLen-1, 0, &tailRep);
+	    ListObjReplaceRepAndInvalidate(listObj, &tailRep);
+	    return TCL_OK;
+	} else if ((first+numToDelete) >= origListLen) {
+	    /* Delete from tail, so return head */
+            /* T:listrep-1.{8,9},2.{6,7},3.{17,18},4.8 */
+	    ListRep headRep;
+	    ListRepRange(&listRep, 0, first-1, 0, &headRep);
+	    ListObjReplaceRepAndInvalidate(listObj, &headRep);
+	    return TCL_OK;
+	}
+	/* Deletion from middle. Fall through to general case */
     }
-    if (count < 0) {
-	count = 0;
-    } else if (count > LIST_MAX /* Handle integer overflow */
-	    || numElems < first+count) {
 
-	count = numElems - first;
-    }
+    /* Garbage collect before checking the pure insert optimization */
+    ListRepFreeUnreferenced(&listRep);
 
-    if (objc > LIST_MAX - (numElems - count)) {
-	if (interp != NULL) {
-	    Tcl_SetObjResult(interp, Tcl_ObjPrintf(
-		    "max length of a Tcl list (%d elements) exceeded",
-		    LIST_MAX));
+    /*
+     * Check Case (2) - pure inserts under certain conditions:
+     */
+    if (numToDelete == 0) {
+	/* Case (2a) - Append to list. */
+	if (first == origListLen) {
+            /* T:listrep-1.11,2.9,3.{5,6},2.2.1 */
+	    return TclListObjAppendElements(
+		interp, listObj, numToInsert, insertObjs);
+	}
+
+	/*
+	 * Case (2b) - pure inserts at front under some circumstances
+	 * (i) Insertion must be at head of list
+	 * (ii) The list's span must be at head of the in-use slots in the store
+	 * (iii) There must be unused room at front of the store
+	 * NOTE THIS IS TRUE EVEN IF THE ListStore IS SHARED as it will not
+	 * affect the other Tcl_Obj's referencing this ListStore.
+	 */
+	if (first == 0 &&                                            /* (i) */
+	    ListRepStart(&listRep) == listRep.storePtr->firstUsed && /* (ii) */
+	    numToInsert <= listRep.storePtr->firstUsed               /* (iii) */
+	) {
+	    ListSizeT newLen;
+	    LIST_ASSERT(numToInsert); /* Else would have returned above */
+	    listRep.storePtr->firstUsed -= numToInsert;
+	    ObjArrayCopy(&listRep.storePtr->slots[listRep.storePtr->firstUsed],
+			 numToInsert,
+			 insertObjs);
+	    listRep.storePtr->numUsed += numToInsert;
+	    newLen = listRep.spanPtr->spanLength + numToInsert;
+	    if (listRep.spanPtr && listRep.spanPtr->refCount <= 1) {
+		/* An unshared span record, re-use it */
+                /* T:listrep-3.1 */
+		listRep.spanPtr->spanStart = listRep.storePtr->firstUsed;
+		listRep.spanPtr->spanLength = newLen;
+	    } else {
+		/* Need a new span record */
+		if (listRep.storePtr->firstUsed == 0) {
+		    listRep.spanPtr = NULL;
+		} else {
+                    /* T:listrep-4.3 */
+		    listRep.spanPtr =
+			ListSpanNew(listRep.storePtr->firstUsed, newLen);
+		}
+	    }
+	    ListObjReplaceRepAndInvalidate(listObj, &listRep);
+	    return TCL_OK;
 	}
-	return TCL_ERROR;
     }
-    isShared = (listRepPtr->refCount > 1);
-    numRequired = numElems - count + objc; /* Known <= LIST_MAX */
-    needGrow = numRequired > listRepPtr->maxElemCount;
 
-    for (i = 0;  i < objc;  i++) {
-	Tcl_IncrRefCount(objv[i]);
+    /* Just for readability of the code */
+    lenChange = numToInsert - numToDelete;
+    leadSegmentLen = first;
+    tailSegmentLen = origListLen - (first + numToDelete);
+    numFreeSlots = listRep.storePtr->numAllocated - listRep.storePtr->numUsed;
+
+    /*
+     * Before further processing, if unshared, try and reallocate to avoid
+     * new allocation below. This avoids expensive ref count manipulation
+     * later by not having to go through the ListRepInit and
+     * ListObjReplaceAndInvalidate below.
+     * TODO - we could be smarter about the reallocate. Use of realloc
+     * means all new free space is at the back. Instead, the realloc could
+     * be an explicit alloc and memmove which would let us redistribute
+     * free space.
+     */
+    if (numFreeSlots < lenChange && !ListRepIsShared(&listRep)) {
+	/* T:listrep-1.{1,3,14,18,21},3.{3,10,11,14,27,32,41} */
+	ListStore *newStorePtr =
+	    ListStoreReallocate(listRep.storePtr, origListLen + lenChange);
+	if (newStorePtr == NULL) {
+	    return MemoryAllocationError(interp,
+					 LIST_SIZE(origListLen + lenChange));
+	}
+	listRep.storePtr = newStorePtr;
+	numFreeSlots =
+	    listRep.storePtr->numAllocated - listRep.storePtr->numUsed;
+	/*
+	 * WARNING: at this point the Tcl_Obj internal rep potentially
+	 * points to freed storage if the reallocation returned a
+	 * different location. Overwrite it to bring it back in sync.
+	 */
+	ListObjStompRep(listObj, &listRep);
     }
 
-    if (needGrow && !isShared) {
-	/* Try to use realloc */
-	List *newPtr = NULL;
-	int attempt = 2 * numRequired;
-	if (attempt <= LIST_MAX) {
-	    newPtr = (List *)attemptckrealloc(listRepPtr, LIST_SIZE(attempt));
+    /*
+     * Case (3) a new ListStore is required
+     * (a) The passed-in ListStore is shared
+     * (b) There is not enough free space in the unshared passed-in ListStore
+     * (c) The new unshared size is much "smaller" (TODO) than the allocated space
+     * TODO - for unshared case ONLY, consider a "move" based implementation
+     */
+    if (ListRepIsShared(&listRep) || /* 3a */
+	numFreeSlots < lenChange ||  /* 3b */
+	(origListLen + lenChange) < (listRep.storePtr->numAllocated / 4) /* 3c */
+    ) {
+	ListRep newRep;
+	Tcl_Obj **toObjs;
+	listObjs = &listRep.storePtr->slots[ListRepStart(&listRep)];
+	ListRepInit(origListLen + lenChange,
+		    NULL,
+		    LISTREP_PANIC_ON_FAIL | favor,
+		    &newRep);
+	toObjs = ListRepSlotPtr(&newRep, 0);
+	if (leadSegmentLen > 0) {
+            /* T:listrep-2.{2,3,13:18},4.{6,9,13:18} */
+	    ObjArrayCopy(toObjs, leadSegmentLen, listObjs);
 	}
-	if (newPtr == NULL) {
-	    attempt = numRequired + 1 + TCL_MIN_ELEMENT_GROWTH;
-	    if (attempt > LIST_MAX) {
-		attempt = LIST_MAX;
-	    }
-	    newPtr = (List *)attemptckrealloc(listRepPtr, LIST_SIZE(attempt));
+	if (numToInsert > 0) {
+            /* T:listrep-2.{1,2,3,10:18},4.{1,2,4,6,10:18} */
+	    ObjArrayCopy(&toObjs[leadSegmentLen],
+			 numToInsert,
+			 insertObjs);
 	}
-	if (newPtr == NULL) {
-	    attempt = numRequired;
-	    newPtr = (List *)attemptckrealloc(listRepPtr, LIST_SIZE(attempt));
+	if (tailSegmentLen > 0) {
+            /* T:listrep-2.{1,2,3,10:15},4.{1,2,4,6,9:12,16:18} */
+	    ObjArrayCopy(&toObjs[leadSegmentLen + numToInsert],
+			 tailSegmentLen,
+			 &listObjs[leadSegmentLen+numToDelete]);
 	}
-	if (newPtr) {
-	    listRepPtr = newPtr;
-	    ListResetInternalRep(listPtr, listRepPtr);
-	    elemPtrs = listRepPtr->elements;
-	    listRepPtr->maxElemCount = attempt;
-	    needGrow = numRequired > listRepPtr->maxElemCount;
+	newRep.storePtr->numUsed = origListLen + lenChange;
+	if (newRep.spanPtr) {
+            /* T:listrep-2.{1,2,3,10:18},4.{1,2,4,6,9:18} */
+	    newRep.spanPtr->spanLength = newRep.storePtr->numUsed;
 	}
+	LISTREP_CHECK(&newRep);
+	ListObjReplaceRepAndInvalidate(listObj, &newRep);
+	return TCL_OK;
     }
-    if (!needGrow && !isShared) {
-	int shift;
 
-	/*
-	 * Can use the current List struct. First "delete" count elements
-	 * starting at first.
-	 */
+    /*
+     * Case (4) - unshared ListStore with sufficient room.
+     * After deleting elements, there will be a corresponding gap. If this
+     * gap does not match number of insertions, either the lead segment,
+     * or the tail segment, or both will have to be moved.
+     * The general strategy is to move the fewest number of elements. If
+     *
+     * TODO - what about appends to unshared ? Is below sufficiently optimal?
+     */
 
-	for (j = first;  j < first + count;  j++) {
-	    Tcl_Obj *victimPtr = elemPtrs[j];
+    /* Following must hold for unshared listreps after ListRepFreeUnreferenced above */
+    LIST_ASSERT(origListLen == listRep.storePtr->numUsed);
+    LIST_ASSERT(origListLen == ListRepLength(&listRep));
+    LIST_ASSERT(ListRepStart(&listRep) == listRep.storePtr->firstUsed);
 
-	    TclDecrRefCount(victimPtr);
-	}
+    LIST_ASSERT((numToDelete + numToInsert) > 0);
 
-	/*
-	 * Shift the elements after the last one removed to their new
-	 * locations.
-	 */
+    /* Base of slot array holding the list elements */
+    listObjs = &listRep.storePtr->slots[ListRepStart(&listRep)];
+
+    /*
+     * Free up elements to be deleted. Before that, increment the ref counts
+     * for objects to be inserted in case there is overlap. T:listobj-11.1
+     */
+    if (numToInsert) {
+	/* T:listrep-1.{1,3,12:21},3.{2,3,7:14,23:41} */
+	ObjArrayIncrRefs(insertObjs, 0, numToInsert);
+    }
+    if (numToDelete) {
+        /* T:listrep-1.{6,7,12:21},3.{19:41} */
+	ObjArrayDecrRefs(listObjs, first, numToDelete);
+    }
 
-	start = first + count;
-	numAfterLast = numElems - start;
-	shift = objc - count;	/* numNewElems - numDeleted */
-	if ((numAfterLast > 0) && (shift != 0)) {
-	    Tcl_Obj **src = elemPtrs + start;
+    /*
+     * TODO - below the moves are optimized but this may result in needing a
+     * span allocation. Perhaps for small lists, it may be more efficient to
+     * just move everything up front and save on allocating a span.
+     */
 
-	    memmove(src+shift, src, numAfterLast * sizeof(Tcl_Obj*));
-	}
-    } else {
+    /*
+     * Calculate shifts if necessary to accomodate insertions.
+     * NOTE: all indices are relative to listObjs which is not necessarily the
+     * start of the ListStore storage area.
+     *
+     * leadShift - how much to shift the lead segment
+     * tailShift - how much to shift the tail segment
+     * insertTarget - index where to insert.
+     */
+
+    if (lenChange == 0) {
+	/* T:listrep-1.{12,15,19},3.{23,28,33}. Exact fit */
+	leadShift = 0;
+	tailShift = 0;
+    } else if (lenChange < 0) {
 	/*
-	 * Cannot use the current List struct; it is shared, too small, or
-	 * both. Allocate a new struct and insert elements into it.
+	 * More deletions than insertions. The gap after deletions is large
+	 * enough for insertions. Move a segment depending on size.
 	 */
-
-	List *oldListRepPtr = listRepPtr;
-	Tcl_Obj **oldPtrs = elemPtrs;
-	int newMax;
-
-	if (needGrow) {
-	    newMax = 2 * numRequired;
+	if (leadSegmentLen > tailSegmentLen) {
+	    /* Tail segment smaller. Insert after lead, move tail down */
+            /* T:listrep-1.{7,17,20},3.{21,2229,35} */
+	    leadShift = 0;
+	    tailShift = lenChange;
 	} else {
-	    newMax = listRepPtr->maxElemCount;
+	    /* Lead segment smaller. Insert before tail, move lead up */
+            /* T:listrep-1.{6,13,16},3.{19,20,24,34} */
+	    leadShift = -lenChange;
+	    tailShift = 0;
 	}
+    } else {
+	LIST_ASSERT(lenChange > 0); /* Reminder */
 
-	listRepPtr = AttemptNewList(NULL, newMax, NULL);
-	if (listRepPtr == NULL) {
-	    unsigned int limit = LIST_MAX - numRequired;
-	    unsigned int extra = numRequired - numElems
-		    + TCL_MIN_ELEMENT_GROWTH;
-	    int growth = (int) ((extra > limit) ? limit : extra);
-
-	    listRepPtr = AttemptNewList(NULL, numRequired + growth, NULL);
-	    if (listRepPtr == NULL) {
-		listRepPtr = AttemptNewList(interp, numRequired, NULL);
-		if (listRepPtr == NULL) {
-		    for (i = 0;  i < objc;  i++) {
-			/* See bug 3598580 */
-#if TCL_MAJOR_VERSION > 8
-			Tcl_DecrRefCount(objv[i]);
-#else
-			objv[i]->refCount--;
-#endif
-		    }
-		    return TCL_ERROR;
+	/*
+	 * We need to make room for the insertions. Again we have multiple
+	 * possibilities. We may be able to get by just shifting one segment
+	 * or need to shift both. In the former case, favor shifting the
+	 * smaller segment.
+	 */
+	int leadSpace = ListRepNumFreeHead(&listRep);
+	int tailSpace = ListRepNumFreeTail(&listRep);
+	int finalFreeSpace = leadSpace + tailSpace - lenChange;
+
+	LIST_ASSERT((leadSpace + tailSpace) >= lenChange);
+	if (leadSpace >= lenChange
+	    && (leadSegmentLen < tailSegmentLen || tailSpace < lenChange)) {
+	    /* Move only lead to the front to make more room */
+            /* T:listrep-3.25,36,38, */
+	    leadShift = -lenChange;
+	    tailShift = 0;
+	    /*
+	     * Redistribute the remaining free space between the front and
+	     * back if either there is no tail space left or if the
+	     * entire list is the head anyways. This is an important
+	     * optimization for further operations like further asymmetric
+	     * insertions.
+	     */
+	    if (finalFreeSpace > 1 && (tailSpace == 0 || tailSegmentLen == 0)) {
+		int postShiftLeadSpace = leadSpace - lenChange;
+		if (postShiftLeadSpace > (finalFreeSpace/2)) {
+		    ListSizeT extraShift = postShiftLeadSpace - (finalFreeSpace / 2);
+		    leadShift -= extraShift;
+		    tailShift = -extraShift; /* Move tail to the front as well */
 		}
-	    }
-	}
-
-	ListResetInternalRep(listPtr, listRepPtr);
-	listRepPtr->refCount++;
-
-	elemPtrs = listRepPtr->elements;
-
-	if (isShared) {
+	    } /* else T:listrep-3.{7,12,25,38} */
+	    LIST_ASSERT(leadShift >= 0 || leadSpace >= -leadShift);
+	} else if (tailSpace >= lenChange) {
+	    /* Move only tail segment to the back to make more room. */
+            /* T:listrep-3.{8,10,11,14,26,27,30,32,37,39,41} */
+	    leadShift = 0;
+	    tailShift = lenChange;
 	    /*
-	     * The old struct will remain in place; need new refCounts for the
-	     * new List struct references. Copy over only the surviving
-	     * elements.
+	     * See comments above. This is analogous.
 	     */
-
-	    for (i=0; i < first; i++) {
-		elemPtrs[i] = oldPtrs[i];
-		Tcl_IncrRefCount(elemPtrs[i]);
-	    }
-	    for (i = first + count, j = first + objc;
-		    j < numRequired; i++, j++) {
-		elemPtrs[j] = oldPtrs[i];
-		Tcl_IncrRefCount(elemPtrs[j]);
+	    if (finalFreeSpace > 1 && (leadSpace == 0 || leadSegmentLen == 0)) {
+		int postShiftTailSpace = tailSpace - lenChange;
+		if (postShiftTailSpace > (finalFreeSpace/2)) {
+		    /* T:listrep-1.{1,3,14,18,21},3.{2,3,26,27} */
+		    ListSizeT extraShift = postShiftTailSpace - (finalFreeSpace / 2);
+		    tailShift += extraShift;
+		    leadShift = extraShift; /* Move head to the back as well */
+		}
 	    }
-
-	    oldListRepPtr->refCount--;
+	    LIST_ASSERT(tailShift <= tailSpace);
 	} else {
 	    /*
-	     * The old struct will be removed; use its inherited refCounts.
+	     * Both lead and tail need to be shifted to make room.
+	     * Divide remaining free space equally between front and back.
 	     */
-
-	    if (first > 0) {
-		memcpy(elemPtrs, oldPtrs, first * sizeof(Tcl_Obj *));
-	    }
+            /* T:listrep-3.{9,13,31,40} */
+	    LIST_ASSERT(leadSpace < lenChange);
+	    LIST_ASSERT(tailSpace < lenChange);
 
 	    /*
-	     * "Delete" count elements starting at first.
+	     * leadShift = leadSpace - (finalFreeSpace/2)
+	     * Thus leadShift <= leadSpace
+	     * Also,
+	     * = leadSpace - (leadSpace + tailSpace - lenChange)/2
+	     * = leadSpace/2 - tailSpace/2 + lenChange/2
+	     * >= 0 because lenChange > tailSpace
 	     */
-
-	    for (j = first;  j < first + count;  j++) {
-		Tcl_Obj *victimPtr = oldPtrs[j];
-
-		TclDecrRefCount(victimPtr);
+	    leadShift = leadSpace - (finalFreeSpace / 2);
+	    tailShift = lenChange - leadShift;
+	    if (tailShift > tailSpace) {
+		/* Account for integer division errors */
+		leadShift += 1;
+		tailShift -= 1;
 	    }
-
 	    /*
-	     * Copy the elements after the last one removed, shifted to their
-	     * new locations.
+	     * Following must be true because otherwise one of the previous
+	     * if clauses would have been taken.
 	     */
-
-	    start = first + count;
-	    numAfterLast = numElems - start;
-	    if (numAfterLast > 0) {
-		memcpy(elemPtrs + first + objc, oldPtrs + start,
-			(size_t) numAfterLast * sizeof(Tcl_Obj *));
-	    }
-
-	    ckfree(oldListRepPtr);
+	    LIST_ASSERT(leadShift > 0 && leadShift < lenChange);
+	    LIST_ASSERT(tailShift > 0 && tailShift < lenChange);
+	    leadShift = -leadShift; /* Lead is actually shifted downward */
 	}
     }
 
-    /*
-     * Insert the new elements into elemPtrs before "first".
-     */
-
-    for (i=0,j=first ; i<objc ; i++,j++) {
-	elemPtrs[j] = objv[i];
+    /* Careful about order of moves! */
+    if (leadShift > 0) {
+	/* Will happen when we have to make room at bottom */
+	if (tailShift != 0 && tailSegmentLen != 0) {
+            /* T:listrep-1.{1,3,14,18},3.{2,3,26,27} */
+	    ListSizeT tailStart = leadSegmentLen + numToDelete;
+	    memmove(&listObjs[tailStart + tailShift],
+		    &listObjs[tailStart],
+		    tailSegmentLen * sizeof(Tcl_Obj *));
+	}
+	if (leadSegmentLen != 0) {
+            /* T:listrep-1.{3,6,16,18,21},3.{19,20,34} */
+	    memmove(&listObjs[leadShift],
+		    &listObjs[0],
+		    leadSegmentLen * sizeof(Tcl_Obj *));
+	}
+    } else {
+	if (leadShift != 0 && leadSegmentLen != 0) {
+            /* T:listrep-3.{7,9,12,13,31,36,38,40} */
+	    memmove(&listObjs[leadShift],
+		    &listObjs[0],
+		    leadSegmentLen * sizeof(Tcl_Obj *));
+	}
+	if (tailShift != 0 && tailSegmentLen != 0) {
+            /* T:listrep-1.{7,17},3.{8:11,13,14,21,22,35,37,39:41} */
+	    ListSizeT tailStart = leadSegmentLen + numToDelete;
+	    memmove(&listObjs[tailStart + tailShift],
+		    &listObjs[tailStart],
+		    tailSegmentLen * sizeof(Tcl_Obj *));
+	}
+    }
+    if (numToInsert) {
+	/* Do NOT use ObjArrayCopy here since we have already incr'ed ref counts */
+        /* T:listrep-1.{1,3,12:21},3.{2,3,7:14,23:41} */
+	memmove(&listObjs[leadSegmentLen + leadShift],
+		insertObjs,
+		numToInsert * sizeof(Tcl_Obj *));
     }
 
-    /*
-     * Update the count of elements.
-     */
-
-    listRepPtr->elemCount = numRequired;
-
-    /*
-     * Invalidate and free any old representations that may not agree
-     * with the revised list's internal representation.
-     */
+    listRep.storePtr->firstUsed += leadShift;
+    listRep.storePtr->numUsed = origListLen + lenChange;
+    listRep.storePtr->flags = 0;
 
-    listRepPtr->refCount++;
-    TclFreeInternalRep(listPtr);
-    ListSetInternalRep(listPtr, listRepPtr);
-    listRepPtr->refCount--;
+    if (listRep.spanPtr && listRep.spanPtr->refCount <= 1) {
+	/* An unshared span record, re-use it, even if not required */
+        /* T:listrep-3.{2,3,7:14},3.{19:41} */
+	listRep.spanPtr->spanStart = listRep.storePtr->firstUsed;
+	listRep.spanPtr->spanLength = listRep.storePtr->numUsed;
+    } else {
+	/* Need a new span record */
+	if (listRep.storePtr->firstUsed == 0) {
+            /* T:listrep-1.{7,12,15,17,19,20} */
+	    listRep.spanPtr = NULL;
+	} else {
+            /* T:listrep-1.{1,3,6.1,13,14,16,18,21} */
+	    listRep.spanPtr = ListSpanNew(listRep.storePtr->firstUsed,
+					  listRep.storePtr->numUsed);
+	}
+    }
 
-    TclInvalidateStringRep(listPtr);
+    LISTREP_CHECK(&listRep);
+    ListObjReplaceRepAndInvalidate(listObj, &listRep);
     return TCL_OK;
 }
 
@@ -1217,48 +2508,49 @@ Tcl_ListObjReplace(
  *
  * TclLindexList --
  *
- *	Implements the 'lindex' command when objc==3.
- *
- *	Implemented entirely as a wrapper around 'TclLindexFlat'. Reconfigures
- *	the argument format into required form while taking care to manage
- *	shimmering so as to tend to keep the most useful internalreps
- *	and/or avoid the most expensive conversions.
+ *	This procedure handles the 'lindex' command when objc==3.
  *
- * Value
+ * Results:
+ *	Returns a pointer to the object extracted, or NULL if an error
+ *	occurred. The returned object already includes one reference count for
+ *	the pointer returned.
  *
- *	A pointer to the specified element, with its 'refCount' incremented, or
- *	NULL if an error occurred.
+ * Side effects:
+ *	None.
  *
- * Notes
+ * Notes:
+ *	This procedure is implemented entirely as a wrapper around
+ *	TclLindexFlat. All it does is reconfigure the argument format into the
+ *	form required by TclLindexFlat, while taking care to manage shimmering
+ *	in such a way that we tend to keep the most useful internalreps and/or
+ *	avoid the most expensive conversions.
  *
  *----------------------------------------------------------------------
  */
-
 Tcl_Obj *
 TclLindexList(
     Tcl_Interp *interp,		/* Tcl interpreter. */
-    Tcl_Obj *listPtr,		/* List being unpacked. */
-    Tcl_Obj *argPtr)		/* Index or index list. */
+    Tcl_Obj *listObj,		/* List being unpacked. */
+    Tcl_Obj *argObj)		/* Index or index list. */
 {
-
-    int index;			/* Index into the list. */
+    ListSizeT index;			/* Index into the list. */
     Tcl_Obj *indexListCopy;
-    List *listRepPtr;
+    Tcl_Obj **indexObjs;
+    ListSizeT numIndexObjs;
 
     /*
      * Determine whether argPtr designates a list or a single index. We have
      * to be careful about the order of the checks to avoid repeated
-     * shimmering; see TIP#22 and TIP#33 for the details.
+     * shimmering; if internal rep is already a list do not shimmer it.
+     * see TIP#22 and TIP#33 for the details.
      */
-
-    ListGetInternalRep(argPtr, listRepPtr);
-    if ((listRepPtr == NULL)
-	    && TclGetIntForIndexM(NULL , argPtr, INT_MAX - 1, &index) == TCL_OK) {
+    if (!TclHasInternalRep(argObj, &tclListType)
+	&& TclGetIntForIndexM(NULL, argObj, ListSizeT_MAX - 1, &index)
+	       == TCL_OK) {
 	/*
 	 * argPtr designates a single index.
 	 */
-
-	return TclLindexFlat(interp, listPtr, 1, &argPtr);
+	return TclLindexFlat(interp, listObj, 1, &argObj);
     }
 
     /*
@@ -1273,61 +2565,61 @@ TclLindexList(
      * implementation does not.
      */
 
-    indexListCopy = TclListObjCopy(NULL, argPtr);
+    indexListCopy = TclListObjCopy(NULL, argObj);
     if (indexListCopy == NULL) {
 	/*
-	 * argPtr designates something that is neither an index nor a
-	 * well-formed list. Report the error via TclLindexFlat.
+	 * The argument is neither an index nor a well-formed list.
+	 * Report the error via TclLindexFlat.
+	 * TODO - This is as original. why not directly return an error?
 	 */
-
-	return TclLindexFlat(interp, listPtr, 1, &argPtr);
+	return TclLindexFlat(interp, listObj, 1, &argObj);
     }
 
-    ListGetInternalRep(indexListCopy, listRepPtr);
-
-    assert(listRepPtr != NULL);
-
-    listPtr = TclLindexFlat(interp, listPtr, listRepPtr->elemCount,
-		listRepPtr->elements);
+    ListObjGetElements(indexListCopy, numIndexObjs, indexObjs);
+    listObj = TclLindexFlat(interp, listObj, numIndexObjs, indexObjs);
     Tcl_DecrRefCount(indexListCopy);
-    return listPtr;
+    return listObj;
 }
 
 /*
  *----------------------------------------------------------------------
  *
- *  TclLindexFlat --
- *
- * 	The core of the 'lindex' command, with all index
- * 	arguments presented as a flat list.
+ * TclLindexFlat --
  *
- *  Value
+ *	This procedure is the core of the 'lindex' command, with all index
+ *	arguments presented as a flat list.
  *
- *	A pointer to the object extracted, with its 'refCount' incremented,  or
- *	NULL if an error occurred.  Thus, the calling code will usually do
- *	something like:
+ * Results:
+ *	Returns a pointer to the object extracted, or NULL if an error
+ *	occurred. The returned object already includes one reference count for
+ *	the pointer returned.
  *
- * 		Tcl_SetObjResult(interp, result);
- * 		Tcl_DecrRefCount(result);
+ * Side effects:
+ *	None.
  *
+ * Notes:
+ *	The reference count of the returned object includes one reference
+ *	corresponding to the pointer returned. Thus, the calling code will
+ *	usually do something like:
+ *		Tcl_SetObjResult(interp, result);
+ *		Tcl_DecrRefCount(result);
  *
  *----------------------------------------------------------------------
  */
-
 Tcl_Obj *
 TclLindexFlat(
     Tcl_Interp *interp,		/* Tcl interpreter. */
-    Tcl_Obj *listPtr,		/* Tcl object representing the list. */
-    int indexCount,		/* Count of indices. */
+    Tcl_Obj *listObj,		/* Tcl object representing the list. */
+    ListSizeT indexCount,		/* Count of indices. */
     Tcl_Obj *const indexArray[])/* Array of pointers to Tcl objects that
 				 * represent the indices in the list. */
 {
-    int i;
+    ListSizeT i;
 
-    Tcl_IncrRefCount(listPtr);
+    Tcl_IncrRefCount(listObj);
 
-    for (i=0 ; i<indexCount && listPtr ; i++) {
-	int index, listLen = 0;
+    for (i=0 ; i<indexCount && listObj ; i++) {
+	ListSizeT index, listLen = 0;
 	Tcl_Obj **elemPtrs = NULL, *sublistCopy;
 
 	/*
@@ -1336,18 +2628,16 @@ TclLindexFlat(
 	 * while we are still using it. See test lindex-8.4.
 	 */
 
-	sublistCopy = TclListObjCopy(interp, listPtr);
-	Tcl_DecrRefCount(listPtr);
-	listPtr = NULL;
+	sublistCopy = TclListObjCopy(interp, listObj);
+	Tcl_DecrRefCount(listObj);
+	listObj = NULL;
 
 	if (sublistCopy == NULL) {
-	    /*
-	     * The sublist is not a list at all => error.
-	     */
-
+	    /* The sublist is not a list at all => error.  */
 	    break;
 	}
-	TclListObjGetElementsM(NULL, sublistCopy, &listLen, &elemPtrs);
+	LIST_ASSERT_TYPE(sublistCopy);
+	ListObjGetElements(sublistCopy, listLen, elemPtrs);
 
 	if (TclGetIntForIndexM(interp, indexArray[i], /*endValue*/ listLen-1,
 		&index) == TCL_OK) {
@@ -1358,26 +2648,24 @@ TclLindexFlat(
 		 */
 
 		while (++i < indexCount) {
-		    if (TclGetIntForIndexM(interp, indexArray[i], INT_MAX - 1, &index)
+		    if (TclGetIntForIndexM(
+			    interp, indexArray[i], ListSizeT_MAX - 1, &index)
 			!= TCL_OK) {
 			Tcl_DecrRefCount(sublistCopy);
 			return NULL;
 		    }
 		}
-		TclNewObj(listPtr);
+		TclNewObj(listObj);
 	    } else {
-		/*
-		 * Extract the pointer to the appropriate element.
-		 */
-
-		listPtr = elemPtrs[index];
+		/* Extract the pointer to the appropriate element. */
+		listObj = elemPtrs[index];
 	    }
-	    Tcl_IncrRefCount(listPtr);
+	    Tcl_IncrRefCount(listObj);
 	}
 	Tcl_DecrRefCount(sublistCopy);
     }
 
-    return listPtr;
+    return listObj;
 }
 
 /*
@@ -1385,34 +2673,39 @@ TclLindexFlat(
  *
  * TclLsetList --
  *
- *	The core of [lset] when objc == 4. Objv[2] may be either a
+ *	Core of the 'lset' command when objc == 4. Objv[2] may be either a
  *	scalar index or a list of indices.
  *      It also handles 'lpop' when given a NULL value.
  *
- *	Implemented entirely as a wrapper around 'TclLindexFlat', as described
- *	for 'TclLindexList'.
+ * Results:
+ *	Returns the new value of the list variable, or NULL if there was an
+ *	error. The returned object includes one reference count for the
+ *	pointer returned.
  *
- * Value
+ * Side effects:
+ *	None.
  *
- *	The new list, with the 'refCount' of 'valuPtr' incremented, or NULL if
- *	there was an error.
+ * Notes:
+ *	This procedure is implemented entirely as a wrapper around
+ *	TclLsetFlat. All it does is reconfigure the argument format into the
+ *	form required by TclLsetFlat, while taking care to manage shimmering
+ *	in such a way that we tend to keep the most useful internalreps and/or
+ *	avoid the most expensive conversions.
  *
  *----------------------------------------------------------------------
  */
-
 Tcl_Obj *
 TclLsetList(
     Tcl_Interp *interp,		/* Tcl interpreter. */
-    Tcl_Obj *listPtr,		/* Pointer to the list being modified. */
-    Tcl_Obj *indexArgPtr,	/* Index or index-list arg to 'lset'. */
-    Tcl_Obj *valuePtr)		/* Value arg to 'lset' or NULL to 'lpop'. */
+    Tcl_Obj *listObj,		/* Pointer to the list being modified. */
+    Tcl_Obj *indexArgObj,	/* Index or index-list arg to 'lset'. */
+    Tcl_Obj *valueObj)		/* Value arg to 'lset' or NULL to 'lpop'. */
 {
-    int indexCount = 0;		/* Number of indices in the index list. */
+    ListSizeT indexCount = 0;   /* Number of indices in the index list. */
     Tcl_Obj **indices = NULL;	/* Vector of indices in the index list. */
-    Tcl_Obj *retValuePtr;	/* Pointer to the list to be returned. */
-    int index;			/* Current index in the list - discarded. */
+    Tcl_Obj *retValueObj;	/* Pointer to the list to be returned. */
+    ListSizeT index;            /* Current index in the list - discarded. */
     Tcl_Obj *indexListCopy;
-    List *listRepPtr;
 
     /*
      * Determine whether the index arg designates a list or a single index.
@@ -1420,36 +2713,33 @@ TclLsetList(
      * shimmering; see TIP #22 and #23 for details.
      */
 
-    ListGetInternalRep(indexArgPtr, listRepPtr);
-    if (listRepPtr == NULL
-	    && TclGetIntForIndexM(NULL, indexArgPtr, INT_MAX - 1, &index) == TCL_OK) {
-	/*
-	 * indexArgPtr designates a single index.
-	 */
-
-	return TclLsetFlat(interp, listPtr, 1, &indexArgPtr, valuePtr);
-
+    if (!TclHasInternalRep(indexArgObj, &tclListType)
+	&& TclGetIntForIndexM(NULL, indexArgObj, ListSizeT_MAX - 1, &index)
+	       == TCL_OK) {
+	/* indexArgPtr designates a single index. */
+        /* T:listrep-1.{2.1,12.1,15.1,19.1},2.{2.3,9.3,10.1,13.1,16.1}, 3.{4,5,6}.3 */
+	return TclLsetFlat(interp, listObj, 1, &indexArgObj, valueObj);
     }
 
-    indexListCopy = TclListObjCopy(NULL, indexArgPtr);
+    indexListCopy = TclListObjCopy(NULL, indexArgObj);
     if (indexListCopy == NULL) {
 	/*
 	 * indexArgPtr designates something that is neither an index nor a
 	 * well formed list. Report the error via TclLsetFlat.
 	 */
-
-	return TclLsetFlat(interp, listPtr, 1, &indexArgPtr, valuePtr);
+	return TclLsetFlat(interp, listObj, 1, &indexArgObj, valueObj);
     }
-    TclListObjGetElementsM(NULL, indexArgPtr, &indexCount, &indices);
+    LIST_ASSERT_TYPE(indexListCopy);
+    ListObjGetElements(indexListCopy, indexCount, indices);
 
     /*
      * Let TclLsetFlat handle the actual lset'ting.
      */
 
-    retValuePtr = TclLsetFlat(interp, listPtr, indexCount, indices, valuePtr);
+    retValueObj = TclLsetFlat(interp, listObj, indexCount, indices, valueObj);
 
     Tcl_DecrRefCount(indexListCopy);
-    return retValuePtr;
+    return retValueObj;
 }
 
 /*
@@ -1460,109 +2750,106 @@ TclLsetList(
  *	Core engine of the 'lset' command.
  *      It also handles 'lpop' when given a NULL value.
  *
- * Value
- *
- *	The resulting list
- *
- *	    The 'refCount' of 'valuePtr' is incremented.  If 'listPtr' was not
- *	    duplicated, its 'refCount' is incremented.  The reference count of
- *	    an unduplicated object is therefore 2 (one for the returned pointer
- *	    and one for the variable that holds it).  The reference count of a
- *	    duplicate object is 1, reflecting that result is the only active
- *	    reference. The caller is expected to store the result in the
- *	    variable and decrement its reference count. (INST_STORE_* does
- *	    exactly this.)
- *
- *	NULL
- *
- *	    An error occurred.  If 'listPtr' was duplicated, the reference
- *	    count on the duplicate is decremented so that it is 0, causing any
- *	    memory allocated by this function to be freed.
- *
- *
- * Effect
- *
- *	On entry, the reference count of 'listPtr' does not reflect any
- *	references held on the stack. The first action of this function is to
- *	determine whether 'listPtr' is shared and to create a duplicate
- *	unshared copy if it is.  The reference count of the duplicate is
- *	incremented. At this point, the reference count is 1 in either case so
- *	that the object is considered unshared.
+ * Results:
+ *	Returns the new value of the list variable, or NULL if an error
+ *	occurred. The returned object includes one reference count for the
+ *	pointer returned.
  *
- *	The unshared list is altered directly to produce the result.
- *	'TclLsetFlat' maintains a linked list of 'Tcl_Obj' values whose string
- *	representations must be spoilt by threading via 'ptr2' of the
- *	two-pointer internal representation. On entry to 'TclLsetFlat', the
- *	values of 'ptr2' are immaterial; on exit, the 'ptr2' field of any
- *	Tcl_Obj that has been modified is set to NULL.
+ * Side effects:
+ *	On entry, the reference count of the variable value does not reflect
+ *	any references held on the stack. The first action of this function is
+ *	to determine whether the object is shared, and to duplicate it if it
+ *	is. The reference count of the duplicate is incremented. At this
+ *	point, the reference count will be 1 for either case, so that the
+ *	object will appear to be unshared.
+ *
+ *	If an error occurs, and the object has been duplicated, the reference
+ *	count on the duplicate is decremented so that it is now 0: this
+ *	dismisses any memory that was allocated by this function.
+ *
+ *	If no error occurs, the reference count of the original object is
+ *	incremented if the object has not been duplicated, and nothing is done
+ *	to a reference count of the duplicate. Now the reference count of an
+ *	unduplicated object is 2 (the returned pointer, plus the one stored in
+ *	the variable). The reference count of a duplicate object is 1,
+ *	reflecting that the returned pointer is the only active reference. The
+ *	caller is expected to store the returned value back in the variable
+ *	and decrement its reference count. (INST_STORE_* does exactly this.)
  *
  *----------------------------------------------------------------------
  */
-
 Tcl_Obj *
 TclLsetFlat(
     Tcl_Interp *interp,		/* Tcl interpreter. */
-    Tcl_Obj *listPtr,		/* Pointer to the list being modified. */
-    int indexCount,		/* Number of index args. */
+    Tcl_Obj *listObj,		/* Pointer to the list being modified. */
+    ListSizeT indexCount,		/* Number of index args. */
     Tcl_Obj *const indexArray[],
 				/* Index args. */
-    Tcl_Obj *valuePtr)		/* Value arg to 'lset' or NULL to 'lpop'. */
+    Tcl_Obj *valueObj)		/* Value arg to 'lset' or NULL to 'lpop'. */
 {
-    int index, len;
+    ListSizeT index, len;
     int result;
-    Tcl_Obj *subListPtr, *retValuePtr, *chainPtr;
-    Tcl_ObjInternalRep *irPtr;
+    Tcl_Obj *subListObj, *retValueObj;
+    Tcl_Obj *pendingInvalidates[10];
+    Tcl_Obj **pendingInvalidatesPtr = pendingInvalidates;
+    ListSizeT numPendingInvalidates = 0;
 
     /*
      * If there are no indices, simply return the new value.  (Without
      * indices, [lset] is a synonym for [set].
-     * [lpop] does not use this but protect for NULL valuePtr just in case.
+     * [lpop] does not use this but protect for NULL valueObj just in case.
      */
 
     if (indexCount == 0) {
-	if (valuePtr != NULL) {
-	    Tcl_IncrRefCount(valuePtr);
+	if (valueObj != NULL) {
+	    Tcl_IncrRefCount(valueObj);
 	}
-	return valuePtr;
+	return valueObj;
     }
 
     /*
      * If the list is shared, make a copy we can modify (copy-on-write).  We
      * use Tcl_DuplicateObj() instead of TclListObjCopy() for a few reasons:
-     * 1) we have not yet confirmed listPtr is actually a list; 2) We make a
+     * 1) we have not yet confirmed listObj is actually a list; 2) We make a
      * verbatim copy of any existing string rep, and when we combine that with
      * the delayed invalidation of string reps of modified Tcl_Obj's
      * implemented below, the outcome is that any error condition that causes
-     * this routine to return NULL, will leave the string rep of listPtr and
+     * this routine to return NULL, will leave the string rep of listObj and
      * all elements to be unchanged.
      */
 
-    subListPtr = Tcl_IsShared(listPtr) ? Tcl_DuplicateObj(listPtr) : listPtr;
+    subListObj = Tcl_IsShared(listObj) ? Tcl_DuplicateObj(listObj) : listObj;
 
     /*
      * Anchor the linked list of Tcl_Obj's whose string reps must be
      * invalidated if the operation succeeds.
      */
 
-    retValuePtr = subListPtr;
-    chainPtr = NULL;
+    retValueObj = subListObj;
     result = TCL_OK;
 
+    /* Allocate if static array for pending invalidations is too small */
+    if (indexCount
+        > (int) (sizeof(pendingInvalidates) / sizeof(pendingInvalidates[0]))) {
+	pendingInvalidatesPtr =
+	    (Tcl_Obj **) ckalloc(indexCount * sizeof(*pendingInvalidatesPtr));
+    }
+
     /*
      * Loop through all the index arguments, and for each one dive into the
      * appropriate sublist.
      */
 
     do {
-	int elemCount;
+	ListSizeT elemCount;
 	Tcl_Obj *parentList, **elemPtrs;
 
 	/*
 	 * Check for the possible error conditions...
 	 */
 
-	if (TclListObjGetElementsM(interp, subListPtr, &elemCount, &elemPtrs)
-		!= TCL_OK) {
+	if (TclListObjGetElementsM(interp, subListObj, &elemCount, &elemPtrs)
+	    != TCL_OK) {
 	    /* ...the sublist we're indexing into isn't a list at all. */
 	    result = TCL_ERROR;
 	    break;
@@ -1574,22 +2861,27 @@ TclLsetFlat(
 	 */
 
 	if (TclGetIntForIndexM(interp, *indexArray, elemCount - 1, &index)
-		!= TCL_OK)  {
+	    != TCL_OK) {
 	    /* ...the index we're trying to use isn't an index at all. */
 	    result = TCL_ERROR;
-	    indexArray++;
+	    indexArray++; /* Why bother with this increment? TBD */
 	    break;
 	}
 	indexArray++;
 
 	if (index < 0 || index > elemCount
-		|| (valuePtr == NULL && index >= elemCount)) {
+	    || (valueObj == NULL && index >= elemCount)) {
 	    /* ...the index points outside the sublist. */
 	    if (interp != NULL) {
-		Tcl_SetObjResult(interp, Tcl_ObjPrintf(
-			"index \"%s\" out of range", Tcl_GetString(indexArray[-1])));
-		Tcl_SetErrorCode(interp, "TCL", "VALUE", "INDEX"
-			"OUTOFRANGE", NULL);
+		Tcl_SetObjResult(interp,
+		                 Tcl_ObjPrintf("index \"%s\" out of range",
+		                               Tcl_GetString(indexArray[-1])));
+		Tcl_SetErrorCode(interp,
+		                 "TCL",
+		                 "VALUE",
+		                 "INDEX"
+		                 "OUTOFRANGE",
+		                 NULL);
 	    }
 	    result = TCL_ERROR;
 	    break;
@@ -1597,128 +2889,129 @@ TclLsetFlat(
 
 	/*
 	 * No error conditions.  As long as we're not yet on the last index,
-	 * determine the next sublist for the next pass through the loop, and
-	 * take steps to make sure it is an unshared copy, as we intend to
-	 * modify it.
+	 * determine the next sublist for the next pass through the loop,
+	 * and take steps to make sure it is an unshared copy, as we intend
+	 * to modify it.
 	 */
 
 	if (--indexCount) {
-	    parentList = subListPtr;
+	    parentList = subListObj;
 	    if (index == elemCount) {
-		TclNewObj(subListPtr);
+		TclNewObj(subListObj);
 	    } else {
-		subListPtr = elemPtrs[index];
+		subListObj = elemPtrs[index];
 	    }
-	    if (Tcl_IsShared(subListPtr)) {
-		subListPtr = Tcl_DuplicateObj(subListPtr);
+	    if (Tcl_IsShared(subListObj)) {
+		subListObj = Tcl_DuplicateObj(subListObj);
 	    }
 
 	    /*
 	     * Replace the original elemPtr[index] in parentList with a copy
 	     * we know to be unshared.  This call will also deal with the
 	     * situation where parentList shares its internalrep with other
-	     * Tcl_Obj's.  Dealing with the shared internalrep case can cause
-	     * subListPtr to become shared again, so detect that case and make
-	     * and store another copy.
+	     * Tcl_Obj's.  Dealing with the shared internalrep case can
+	     * cause subListObj to become shared again, so detect that case
+	     * and make and store another copy.
 	     */
 
 	    if (index == elemCount) {
-		Tcl_ListObjAppendElement(NULL, parentList, subListPtr);
+		Tcl_ListObjAppendElement(NULL, parentList, subListObj);
 	    } else {
-		TclListObjSetElement(NULL, parentList, index, subListPtr);
+		TclListObjSetElement(NULL, parentList, index, subListObj);
 	    }
-	    if (Tcl_IsShared(subListPtr)) {
-		subListPtr = Tcl_DuplicateObj(subListPtr);
-		TclListObjSetElement(NULL, parentList, index, subListPtr);
+	    if (Tcl_IsShared(subListObj)) {
+		subListObj = Tcl_DuplicateObj(subListObj);
+		TclListObjSetElement(NULL, parentList, index, subListObj);
 	    }
 
 	    /*
-	     * The TclListObjSetElement() calls do not spoil the string rep of
-	     * parentList, and that's fine for now, since all we've done so
-	     * far is replace a list element with an unshared copy.  The list
-	     * value remains the same, so the string rep. is still valid, and
-	     * unchanged, which is good because if this whole routine returns
-	     * NULL, we'd like to leave no change to the value of the lset
-	     * variable.  Later on, when we set valuePtr in its proper place,
-	     * then all containing lists will have their values changed, and
-	     * will need their string reps spoiled.  We maintain a list of all
-	     * those Tcl_Obj's (via a little internalrep surgery) so we can spoil
-	     * them at that time.
+	     * The TclListObjSetElement() calls do not spoil the string rep
+	     * of parentList, and that's fine for now, since all we've done
+	     * so far is replace a list element with an unshared copy.  The
+	     * list value remains the same, so the string rep. is still
+	     * valid, and unchanged, which is good because if this whole
+	     * routine returns NULL, we'd like to leave no change to the
+	     * value of the lset variable.  Later on, when we set valueObj
+	     * in its proper place, then all containing lists will have
+	     * their values changed, and will need their string reps
+	     * spoiled.  We maintain a list of all those Tcl_Obj's (via a
+	     * little internalrep surgery) so we can spoil them at that
+	     * time.
 	     */
 
-	    irPtr = TclFetchInternalRep(parentList, &tclListType);
-	    irPtr->twoPtrValue.ptr2 = chainPtr;
-	    chainPtr = parentList;
+	    pendingInvalidatesPtr[numPendingInvalidates] = parentList;
+	    ++numPendingInvalidates;
 	}
     } while (indexCount > 0);
 
     /*
      * Either we've detected and error condition, and exited the loop with
      * result == TCL_ERROR, or we've successfully reached the last index, and
-     * we're ready to store valuePtr.  In either case, we need to clean up our
-     * string spoiling list of Tcl_Obj's.
+     * we're ready to store valueObj. On success, we need to invalidate
+     * the string representations of intermediate lists whose contained
+     * list element would have changed.
      */
+    if (result == TCL_OK) {
+	while (numPendingInvalidates > 0) {
+	    Tcl_Obj *objPtr;
 
-    while (chainPtr) {
-	Tcl_Obj *objPtr = chainPtr;
-	List *listRepPtr;
-
-	/*
-	 * Clear away our internalrep surgery mess.
-	 */
-
-	irPtr = TclFetchInternalRep(objPtr, &tclListType);
-	listRepPtr = (List *)irPtr->twoPtrValue.ptr1;
-	chainPtr = (Tcl_Obj *)irPtr->twoPtrValue.ptr2;
-
-	if (result == TCL_OK) {
-
-	    /*
-	     * We're going to store valuePtr, so spoil string reps of all
-	     * containing lists.
-	     */
+	    --numPendingInvalidates;
+	    objPtr = pendingInvalidatesPtr[numPendingInvalidates];
 
-	    listRepPtr->refCount++;
-	    TclFreeInternalRep(objPtr);
-	    ListSetInternalRep(objPtr, listRepPtr);
-	    listRepPtr->refCount--;
-
-	    TclInvalidateStringRep(objPtr);
-	} else {
-	    irPtr->twoPtrValue.ptr2 = NULL;
+	    if (result == TCL_OK) {
+		/*
+		 * We're going to store valueObj, so spoil string reps of all
+		 * containing lists.
+		 * TODO - historically, the storing of the internal rep was done
+		 * because the ptr2 field of the internal rep was used to chain
+		 * objects whose string rep needed to be invalidated. Now this
+		 * is no longer the case, so replacing of the internal rep
+		 * should not be needed. The TclInvalidateStringRep should
+		 * suffice. Formulate a test case before changing.
+		 */
+		ListRep objInternalRep;
+		TclListObjGetRep(NULL, objPtr, &objInternalRep);
+		ListObjReplaceRepAndInvalidate(objPtr, &objInternalRep);
+	    }
 	}
     }
 
+    if (pendingInvalidatesPtr != pendingInvalidates)
+	ckfree(pendingInvalidatesPtr);
+
     if (result != TCL_OK) {
 	/*
 	 * Error return; message is already in interp. Clean up any excess
 	 * memory.
 	 */
 
-	if (retValuePtr != listPtr) {
-	    Tcl_DecrRefCount(retValuePtr);
+	if (retValueObj != listObj) {
+	    Tcl_DecrRefCount(retValueObj);
 	}
 	return NULL;
     }
 
     /*
-     * Store valuePtr in proper sublist and return. The TCL_INDEX_NONE is
-     * to avoid a compiler warning (not a problem because we checked that
-     * we have a proper list - or something convertible to one - above).
+     * Store valueObj in proper sublist and return. The -1 is to avoid a
+     * compiler warning (not a problem because we checked that we have a
+     * proper list - or something convertible to one - above).
      */
 
-    len = TCL_INDEX_NONE;
-    TclListObjLengthM(NULL, subListPtr, &len);
-    if (valuePtr == NULL) {
-	Tcl_ListObjReplace(NULL, subListPtr, index, 1, 0, NULL);
+    len = -1;
+    TclListObjLengthM(NULL, subListObj, &len);
+    if (valueObj == NULL) {
+        /* T:listrep-1.{4.2,5.4,6.1,7.1,8.3},2.{4,5}.4 */
+	Tcl_ListObjReplace(NULL, subListObj, index, 1, 0, NULL);
     } else if (index == len) {
-	Tcl_ListObjAppendElement(NULL, subListPtr, valuePtr);
+        /* T:listrep-1.2.1,2.{2.3,9.3},3.{4,5,6}.3 */
+	Tcl_ListObjAppendElement(NULL, subListObj, valueObj);
     } else {
-	TclListObjSetElement(NULL, subListPtr, index, valuePtr);
-	TclInvalidateStringRep(subListPtr);
+        /* T:listrep-1.{12.1,15.1,19.1},2.{10,13,16}.1 */
+	TclListObjSetElement(NULL, subListObj, index, valueObj);
+	TclInvalidateStringRep(subListObj);
     }
-    Tcl_IncrRefCount(retValuePtr);
-    return retValuePtr;
+    Tcl_IncrRefCount(retValueObj);
+    return retValueObj;
 }
 
 /*
@@ -1726,93 +3019,53 @@ TclLsetFlat(
  *
  * TclListObjSetElement --
  *
- *	Set a single element of a list to a specified value.
- *
- *	It is the caller's responsibility to invalidate the string
- *	representation of the 'listPtr'.
+ *	Set a single element of a list to a specified value
  *
- * Value
- *
- * 	TCL_OK
- *
- *	    Success.
- *
- *	TCL_ERROR
- *
- *	    'listPtr' does not refer to a list object and cannot be converted
- *	    to one.  An error message will be left in the interpreter result if
- *	    interp is not NULL.
- *
- *	TCL_ERROR
- *
- *	    An index designates an element outside the range [0..listLength-1],
- *	    where 'listLength' is the count of elements in the list object
- *	    designated by 'listPtr'.  An error message is left in the
- *	    interpreter result.
- *
- * Effect
- *
- *	If 'listPtr' designates a shared object, 'Tcl_Panic' is called.  If
- *	'listPtr' is not already of type 'tclListType', it is converted and the
- *	internal representation is unshared. The 'refCount' of the element at
- *	'index' is decremented and replaced in the list with the 'valuePtr',
- *	whose 'refCount' in turn is incremented.
+ * Results:
+ *	The return value is normally TCL_OK. If listObj does not refer to a
+ *	list object and cannot be converted to one, TCL_ERROR is returned and
+ *	an error message will be left in the interpreter result if interp is
+ *	not NULL. Similarly, if index designates an element outside the range
+ *	[0..listLength-1], where listLength is the count of elements in the
+ *	list object designated by listObj, TCL_ERROR is returned and an error
+ *	message is left in the interpreter result.
  *
+ * Side effects:
+ *	Tcl_Panic if listObj designates a shared object. Otherwise, attempts
+ *	to convert it to a list with a non-shared internal rep. Decrements the
+ *	ref count of the object at the specified index within the list,
+ *	replaces with the object designated by valueObj, and increments the
+ *	ref count of the replacement object.
  *
  *----------------------------------------------------------------------
  */
-
 int
 TclListObjSetElement(
     Tcl_Interp *interp,		/* Tcl interpreter; used for error reporting
 				 * if not NULL. */
-    Tcl_Obj *listPtr,		/* List object in which element should be
+    Tcl_Obj *listObj,		/* List object in which element should be
 				 * stored. */
-    int index,			/* Index of element to store. */
-    Tcl_Obj *valuePtr)		/* Tcl object to store in the designated list
+    ListSizeT index,		/* Index of element to store. */
+    Tcl_Obj *valueObj)		/* Tcl object to store in the designated list
 				 * element. */
 {
-    List *listRepPtr;		/* Internal representation of the list being
-				 * modified. */
-    Tcl_Obj **elemPtrs;		/* Pointers to elements of the list. */
-    int elemCount;		/* Number of elements in the list. */
+    ListRep listRep;
+    Tcl_Obj **elemPtrs;         /* Pointers to elements of the list. */
+    ListSizeT elemCount;		/* Number of elements in the list. */
 
-    /*
-     * Ensure that the listPtr parameter designates an unshared list.
-     */
+    /* Ensure that the listObj parameter designates an unshared list. */
 
-    if (Tcl_IsShared(listPtr)) {
+    if (Tcl_IsShared(listObj)) {
 	Tcl_Panic("%s called with shared object", "TclListObjSetElement");
     }
 
-    ListGetInternalRep(listPtr, listRepPtr);
-    if (listRepPtr == NULL) {
-	int result;
-	int length;
-
-	(void) Tcl_GetStringFromObj(listPtr, &length);
-	if (length == 0) {
-	    if (interp != NULL) {
-		Tcl_SetObjResult(interp, Tcl_ObjPrintf(
-			"index \"%d\" out of range", index));
-		Tcl_SetErrorCode(interp, "TCL", "VALUE", "INDEX",
-			"OUTOFRANGE", NULL);
-	    }
-	    return TCL_ERROR;
-	}
-	result = SetListFromAny(interp, listPtr);
-	if (result != TCL_OK) {
-	    return result;
-	}
-	ListGetInternalRep(listPtr, listRepPtr);
+    if (TclListObjGetRep(interp, listObj, &listRep) != TCL_OK) {
+	return TCL_ERROR;
     }
 
-    elemCount = listRepPtr->elemCount;
-
-    /*
-     * Ensure that the index is in bounds.
-     */
+    elemCount = ListRepLength(&listRep);
 
+    /* Ensure that the index is in bounds. */
     if (index<0 || index>=elemCount) {
 	if (interp != NULL) {
 		Tcl_SetObjResult(interp, Tcl_ObjPrintf(
@@ -1824,65 +3077,33 @@ TclListObjSetElement(
     }
 
     /*
-     * If the internal rep is shared, replace it with an unshared copy.
+     * Note - garbage collect this only AFTER checking indices above.
+     * Do not want to modify listrep and then not store it back in listObj.
      */
+    ListRepFreeUnreferenced(&listRep);
 
-    if (listRepPtr->refCount > 1) {
-	Tcl_Obj **dst, **src = listRepPtr->elements;
-	List *newPtr = AttemptNewList(NULL, listRepPtr->maxElemCount, NULL);
+    /* Replace a shared internal rep with an unshared copy */
+    if (listRep.storePtr->refCount > 1) {
+	ListRep newInternalRep;
+        /* T:listrep-2.{10,13,16}.1 */
+	/* TODO - leave extra space? */
+	ListRepClone(&listRep, &newInternalRep, LISTREP_PANIC_ON_FAIL);
+	listRep = newInternalRep;
+    } /* else T:listrep-1.{12.1,15.1,19.1} */
 
-	if (newPtr == NULL) {
-	    newPtr = AttemptNewList(interp, elemCount, NULL);
-	    if (newPtr == NULL) {
-		return TCL_ERROR;
-	    }
-	}
-	newPtr->refCount++;
-	newPtr->elemCount = elemCount;
-	newPtr->canonicalFlag = listRepPtr->canonicalFlag;
-
-	dst = newPtr->elements;
-	while (elemCount--) {
-	    *dst = *src++;
-	    Tcl_IncrRefCount(*dst++);
-	}
-
-	listRepPtr->refCount--;
-
-	listRepPtr = newPtr;
-	ListResetInternalRep(listPtr, listRepPtr);
-    }
-    elemPtrs = listRepPtr->elements;
-
-    /*
-     * Add a reference to the new list element.
-     */
-
-    Tcl_IncrRefCount(valuePtr);
+    /* Retrieve element array AFTER potential cloning above */
+    ListRepElements(&listRep, elemCount, elemPtrs);
 
     /*
-     * Remove a reference from the old list element.
+     * Add a reference to the new list element and remove from old before
+     * replacing it. Order is important!
      */
-
+    Tcl_IncrRefCount(valueObj);
     Tcl_DecrRefCount(elemPtrs[index]);
+    elemPtrs[index] = valueObj;
 
-    /*
-     * Stash the new object in the list.
-     */
-
-    elemPtrs[index] = valuePtr;
-
-    /*
-     * Invalidate outdated internalreps.
-     */
-
-    ListGetInternalRep(listPtr, listRepPtr);
-    listRepPtr->refCount++;
-    TclFreeInternalRep(listPtr);
-    ListSetInternalRep(listPtr, listRepPtr);
-    listRepPtr->refCount--;
-
-    TclInvalidateStringRep(listPtr);
+    /* Internal rep may be cloned so replace */
+    ListObjReplaceRepAndInvalidate(listObj, &listRep);
 
     return TCL_OK;
 }
@@ -1892,34 +3113,33 @@ TclListObjSetElement(
  *
  * FreeListInternalRep --
  *
- *	Deallocate the storage associated with the internal representation of a
- *	a list object.
+ *	Deallocate the storage associated with a list object's internal
+ *	representation.
  *
- * Effect
+ * Results:
+ *	None.
  *
+ * Side effects:
  *	Frees listPtr's List* internal representation, if no longer shared.
  *	May decrement the ref counts of element objects, which may free them.
  *
  *----------------------------------------------------------------------
  */
-
 static void
 FreeListInternalRep(
-    Tcl_Obj *listPtr)		/* List object with internal rep to free. */
+    Tcl_Obj *listObj)		/* List object with internal rep to free. */
 {
-    List *listRepPtr;
-
-    ListGetInternalRep(listPtr, listRepPtr);
-    assert(listRepPtr != NULL);
-
-    if (listRepPtr->refCount-- <= 1) {
-	Tcl_Obj **elemPtrs = listRepPtr->elements;
-	int i, numElems = listRepPtr->elemCount;
-
-	for (i = 0;  i < numElems;  i++) {
-	    Tcl_DecrRefCount(elemPtrs[i]);
-	}
-	ckfree(listRepPtr);
+    ListRep listRep;
+
+    ListObjGetRep(listObj, &listRep);
+    if (listRep.storePtr->refCount-- <= 1) {
+	ObjArrayDecrRefs(
+	    listRep.storePtr->slots,
+	    listRep.storePtr->firstUsed, listRep.storePtr->numUsed);
+	ckfree(listRep.storePtr);
+    }
+    if (listRep.spanPtr) {
+	ListSpanDecrRefs(listRep.spanPtr);
     }
 }
 
@@ -1928,26 +3148,25 @@ FreeListInternalRep(
  *
  * DupListInternalRep --
  *
- *	Initialize the internal representation of a list 'Tcl_Obj' to share the
+ *	Initialize the internal representation of a list Tcl_Obj to share the
  *	internal representation of an existing list object.
  *
- * Effect
+ * Results:
+ *	None.
  *
- *	The 'refCount' of the List internal rep is incremented.
+ * Side effects:
+ *	The reference count of the List internal rep is incremented.
  *
  *----------------------------------------------------------------------
  */
-
 static void
 DupListInternalRep(
-    Tcl_Obj *srcPtr,		/* Object with internal rep to copy. */
-    Tcl_Obj *copyPtr)		/* Object with internal rep to set. */
+    Tcl_Obj *srcObj,		/* Object with internal rep to copy. */
+    Tcl_Obj *copyObj)		/* Object with internal rep to set. */
 {
-    List *listRepPtr;
-
-    ListGetInternalRep(srcPtr, listRepPtr);
-    assert(listRepPtr != NULL);
-    ListSetInternalRep(copyPtr, listRepPtr);
+    ListRep listRep;
+    ListObjGetRep(srcObj, &listRep);
+    ListObjOverwriteRep(copyObj, &listRep);
 }
 
 /*
@@ -1955,31 +3174,26 @@ DupListInternalRep(
  *
  * SetListFromAny --
  *
- *	Convert any object to a list.
- *
- * Value
+ *	Attempt to generate a list internal form for the Tcl object "objPtr".
  *
- *    TCL_OK
- *
- *	Success.  The internal representation of 'objPtr' is set, and the type
- *	of 'objPtr' is 'tclListType'.
- *
- *    TCL_ERROR
- *
- *	An error occured during conversion. An error message is left in the
- *	interpreter's result if 'interp' is not NULL.
+ * Results:
+ *	The return value is TCL_OK or TCL_ERROR. If an error occurs during
+ *	conversion, an error message is left in the interpreter's result
+ *	unless "interp" is NULL.
  *
+ * Side effects:
+ *	If no error occurs, a list is stored as "objPtr"s internal
+ *	representation.
  *
  *----------------------------------------------------------------------
  */
-
 static int
 SetListFromAny(
     Tcl_Interp *interp,		/* Used for error reporting if not NULL. */
     Tcl_Obj *objPtr)		/* The object to convert. */
 {
-    List *listRepPtr;
     Tcl_Obj **elemPtrs;
+    ListRep listRep;
 
     /*
      * Dictionaries are a special case; they have a string representation such
@@ -1993,7 +3207,7 @@ SetListFromAny(
 	Tcl_Obj *keyPtr, *valuePtr;
 	Tcl_DictSearch search;
 	int done;
-	int size;
+	ListSizeT size;
 
 	/*
 	 * Create the new list representation. Note that we do not need to do
@@ -2005,17 +3219,22 @@ SetListFromAny(
 	 */
 
 	Tcl_DictObjSize(NULL, objPtr, &size);
-	listRepPtr = AttemptNewList(interp, size > 0 ? 2*size : 1, NULL);
-	if (!listRepPtr) {
+	/* TODO - leave space in front and/or back? */
+	if (ListRepInitAttempt(
+		interp, size > 0 ? 2 * size : 1, NULL, &listRep)
+	    != TCL_OK) {
 	    return TCL_ERROR;
 	}
-	listRepPtr->elemCount = 2 * size;
 
-	/*
-	 * Populate the list representation.
-	 */
+	LIST_ASSERT(listRep.spanPtr == NULL); /* Guard against future changes */
+	LIST_ASSERT(listRep.storePtr->firstUsed == 0);
+	LIST_ASSERT((listRep.storePtr->flags & LISTSTORE_CANONICAL) == 0);
 
-	elemPtrs = listRepPtr->elements;
+	listRep.storePtr->numUsed = 2 * size;
+
+	/* Populate the list representation. */
+
+	elemPtrs = listRep.storePtr->slots;
 	Tcl_DictObjFirst(NULL, objPtr, &search, &keyPtr, &valuePtr, &done);
 	while (!done) {
 	    *elemPtrs++ = keyPtr;
@@ -2025,7 +3244,7 @@ SetListFromAny(
 	    Tcl_DictObjNext(&search, &keyPtr, &valuePtr, &done);
 	}
     } else {
-	int estCount, length;
+	ListSizeT estCount, length;
 	const char *limit, *nextElem = TclGetStringFromObj(objPtr, &length);
 
 	/*
@@ -2036,29 +3255,32 @@ SetListFromAny(
 	estCount = TclMaxListLength(nextElem, length, &limit);
 	estCount += (estCount == 0);	/* Smallest list struct holds 1
 					 * element. */
-	listRepPtr = AttemptNewList(interp, estCount, NULL);
-	if (listRepPtr == NULL) {
+	/* TODO - allocate additional space? */
+	if (ListRepInitAttempt(interp, estCount, NULL, &listRep)
+	    != TCL_OK) {
 	    return TCL_ERROR;
 	}
-	elemPtrs = listRepPtr->elements;
 
-	/*
-	 * Each iteration, parse and store a list element.
-	 */
+	LIST_ASSERT(listRep.spanPtr == NULL); /* Guard against future changes */
+	LIST_ASSERT(listRep.storePtr->firstUsed == 0);
+
+	elemPtrs = listRep.storePtr->slots;
+
+	/* Each iteration, parse and store a list element. */
 
 	while (nextElem < limit) {
 	    const char *elemStart;
 	    char *check;
-	    int elemSize;
+	    ListSizeT elemSize;
 	    int literal;
 
 	    if (TCL_OK != TclFindElement(interp, nextElem, limit - nextElem,
 		    &elemStart, &nextElem, &elemSize, &literal)) {
-	    fail:
-		while (--elemPtrs >= listRepPtr->elements) {
+fail:
+		while (--elemPtrs >= listRep.storePtr->slots) {
 		    Tcl_DecrRefCount(*elemPtrs);
 		}
-		ckfree(listRepPtr);
+		ckfree(listRep.storePtr);
 		return TCL_ERROR;
 	    }
 	    if (elemStart == limit) {
@@ -2070,11 +3292,7 @@ SetListFromAny(
 	    check = Tcl_InitStringRep(*elemPtrs, literal ? elemStart : NULL,
 		    elemSize);
 	    if (elemSize && check == NULL) {
-		if (interp) {
-		    Tcl_SetObjResult(interp, Tcl_NewStringObj(
-			    "cannot construct list, out of memory", -1));
-		    Tcl_SetErrorCode(interp, "TCL", "MEMORY", NULL);
-		}
+		MemoryAllocationError(interp, elemSize);
 		goto fail;
 	    }
 	    if (!literal) {
@@ -2085,16 +3303,29 @@ SetListFromAny(
 	    Tcl_IncrRefCount(*elemPtrs++);/* Since list now holds ref to it. */
 	}
 
- 	listRepPtr->elemCount = elemPtrs - listRepPtr->elements;
+	listRep.storePtr->numUsed =
+	    elemPtrs - listRep.storePtr->slots;
     }
 
+    LISTREP_CHECK(&listRep);
+
     /*
      * Store the new internalRep. We do this as late
      * as possible to allow the conversion code, in particular
      * Tcl_GetStringFromObj, to use the old internalRep.
      */
 
-    ListSetInternalRep(objPtr, listRepPtr);
+    /*
+     * Note old string representation NOT to be invalidated.
+     * So do NOT use ListObjReplaceRepAndInvalidate. InternalRep to be freed AFTER
+     * IncrRefs so do not use ListObjOverwriteRep
+     */
+    ListRepIncrRefs(&listRep);
+    TclFreeInternalRep(objPtr);
+    objPtr->internalRep.twoPtrValue.ptr1 = listRep.storePtr;
+    objPtr->internalRep.twoPtrValue.ptr2 = listRep.spanPtr;
+    objPtr->typePtr = &tclListType;
+
     return TCL_OK;
 }
 
@@ -2103,69 +3334,71 @@ SetListFromAny(
  *
  * UpdateStringOfList --
  *
- *	Update the string representation for a list object.
+ *	Update the string representation for a list object. Note: This
+ *	function does not invalidate an existing old string rep so storage
+ *	will be lost if this has not already been done.
  *
- *	Any previously-exising string representation is not invalidated, so
- *	storage is lost if this has not been taken care of.
- *
- * Effect
+ * Results:
+ *	None.
  *
- *	The string representation of 'listPtr' is set to the resulting string.
- *	This string will be empty if the list has no elements. It is assumed
- *	that the list internal representation is not NULL.
+ * Side effects:
+ *	The object's string is set to a valid string that results from the
+ *	list-to-string conversion. This string will be empty if the list has
+ *	no elements. The list internal representation should not be NULL and
+ *	we assume it is not NULL.
  *
  *----------------------------------------------------------------------
  */
-
 static void
 UpdateStringOfList(
-    Tcl_Obj *listPtr)		/* List object with string rep to update. */
+    Tcl_Obj *listObj)		/* List object with string rep to update. */
 {
 #   define LOCAL_SIZE 64
     char localFlags[LOCAL_SIZE], *flagPtr = NULL;
-    int numElems, i, length, bytesNeeded = 0;
+    ListSizeT numElems, i, length, bytesNeeded = 0;
     const char *elem, *start;
     char *dst;
     Tcl_Obj **elemPtrs;
-    List *listRepPtr;
-
-    ListGetInternalRep(listPtr, listRepPtr);
+    ListRep listRep;
 
-    assert(listRepPtr != NULL);
+    ListObjGetRep(listObj, &listRep);
+    LISTREP_CHECK(&listRep);
 
-    numElems = listRepPtr->elemCount;
+    ListRepElements(&listRep, numElems, elemPtrs);
 
     /*
      * Mark the list as being canonical; although it will now have a string
      * rep, it is one we derived through proper "canonical" quoting and so
      * it's known to be free from nasties relating to [concat] and [eval].
+     * However, we only do this if this is not a spanned list. Marking the
+     * storage canonical for a spanned list make ALL lists using the storage
+     * canonical which is not right. (Consider a list generated from a
+     * string and then this function called for a spanned list generated
+     * from it). On the other hand, a spanned list is always canonical
+     * (never generated from a string) so it does not have to be explicitly
+     * marked as such. The ListObjIsCanonical macro takes this into account.
+     * See the comments there.
      */
+    if (listRep.spanPtr == NULL) {
+	LIST_ASSERT(listRep.storePtr->firstUsed == 0);/* Invariant */
+	listRep.storePtr->flags |= LISTSTORE_CANONICAL;
+    }
 
-    listRepPtr->canonicalFlag = 1;
-
-    /*
-     * Handle empty list case first, so rest of the routine is simpler.
-     */
+    /* Handle empty list case first, so rest of the routine is simpler. */
 
     if (numElems == 0) {
-	Tcl_InitStringRep(listPtr, NULL, 0);
+	Tcl_InitStringRep(listObj, NULL, 0);
 	return;
     }
 
-    /*
-     * Pass 1: estimate space, gather flags.
-     */
+    /* Pass 1: estimate space, gather flags. */
 
     if (numElems <= LOCAL_SIZE) {
 	flagPtr = localFlags;
     } else {
-	/*
-	 * We know numElems <= LIST_MAX, so this is safe.
-	 */
-
+	/* We know numElems <= LIST_MAX, so this is safe. */
 	flagPtr = (char *)ckalloc(numElems);
     }
-    elemPtrs = listRepPtr->elements;
     for (i = 0; i < numElems; i++) {
 	flagPtr[i] = (i ? TCL_DONT_QUOTE_HASH : 0);
 	elem = TclGetStringFromObj(elemPtrs[i], &length);
@@ -2183,7 +3416,7 @@ UpdateStringOfList(
      * Pass 2: copy into string rep buffer.
      */
 
-    start = dst = Tcl_InitStringRep(listPtr, NULL, bytesNeeded);
+    start = dst = Tcl_InitStringRep(listObj, NULL, bytesNeeded);
     TclOOM(dst, bytesNeeded);
     for (i = 0; i < numElems; i++) {
 	flagPtr[i] |= (i ? TCL_DONT_QUOTE_HASH : 0);
@@ -2193,7 +3426,7 @@ UpdateStringOfList(
     }
 
     /* Set the string length to what was actually written, the safe choice */
-    (void) Tcl_InitStringRep(listPtr, NULL, dst - 1 - start);
+    (void) Tcl_InitStringRep(listObj, NULL, dst - 1 - start);
 
     if (flagPtr != localFlags) {
 	ckfree(flagPtr);
@@ -2201,6 +3434,61 @@ UpdateStringOfList(
 }
 
 /*
+ *------------------------------------------------------------------------
+ *
+ * TclListTestObj --
+ *
+ *    Returns a list object with a specific internal rep and content.
+ *    Used specifically for testing so span can be controlled explicitly.
+ *
+ * Results:
+ *    Pointer to the Tcl_Obj containing the list.
+ *
+ * Side effects:
+ *    None.
+ *
+ *------------------------------------------------------------------------
+ */
+Tcl_Obj *
+TclListTestObj (int length, int leadingSpace, int endSpace)
+{
+    if (length < 0)
+	length = 0;
+    if (leadingSpace < 0)
+	leadingSpace = 0;
+    if (endSpace < 0)
+	endSpace = 0;
+
+    ListRep listRep;
+    ListSizeT capacity;
+    Tcl_Obj *listObj;
+
+    TclNewObj(listObj);
+
+    /* Only a test object so ignoring overflow checks */
+    capacity = length + leadingSpace + endSpace;
+    if (capacity == 0) {
+	return listObj;
+    }
+
+    ListRepInit(capacity, NULL, 0, &listRep);
+
+    ListStore *storePtr = listRep.storePtr;
+    int i;
+    for (i = 0; i < length; ++i) {
+	storePtr->slots[i + leadingSpace] = Tcl_NewIntObj(i);
+	Tcl_IncrRefCount(storePtr->slots[i + leadingSpace]);
+    }
+    storePtr->firstUsed = leadingSpace;
+    storePtr->numUsed = length;
+    if (leadingSpace != 0) {
+	listRep.spanPtr = ListSpanNew(leadingSpace, length);
+    }
+    ListObjReplaceRepAndInvalidate(listObj, &listRep);
+    return listObj;
+}
+
+/*
  * Local Variables:
  * mode: c
  * c-basic-offset: 4
diff --git a/generic/tclOO.c b/generic/tclOO.c
index 0cd08d2..5bd687a 100644
--- a/generic/tclOO.c
+++ b/generic/tclOO.c
@@ -391,9 +391,9 @@ InitFoundation(
      */
 
     TclNewLiteralStringObj(namePtr, "new");
-    Tcl_NewInstanceMethod(interp, (Tcl_Object) fPtr->classCls->thisPtr,
+    TclNewInstanceMethod(interp, (Tcl_Object) fPtr->classCls->thisPtr,
 	    namePtr /* keeps ref */, 0 /* private */, NULL, NULL);
-    fPtr->classCls->constructorPtr = (Method *) Tcl_NewMethod(interp,
+    fPtr->classCls->constructorPtr = (Method *) TclNewMethod(interp,
 	    (Tcl_Class) fPtr->classCls, NULL, 0, &classConstructor, NULL);
 
     /*
@@ -2246,7 +2246,7 @@ CloneObjectMethod(
     Tcl_Obj *namePtr)
 {
     if (mPtr->typePtr == NULL) {
-	Tcl_NewInstanceMethod(interp, (Tcl_Object) oPtr, namePtr,
+	TclNewInstanceMethod(interp, (Tcl_Object) oPtr, namePtr,
 		mPtr->flags & PUBLIC_METHOD, NULL, NULL);
     } else if (mPtr->typePtr->cloneProc) {
 	ClientData newClientData;
@@ -2255,10 +2255,10 @@ CloneObjectMethod(
 		&newClientData) != TCL_OK) {
 	    return TCL_ERROR;
 	}
-	Tcl_NewInstanceMethod(interp, (Tcl_Object) oPtr, namePtr,
+	TclNewInstanceMethod(interp, (Tcl_Object) oPtr, namePtr,
 		mPtr->flags & PUBLIC_METHOD, mPtr->typePtr, newClientData);
     } else {
-	Tcl_NewInstanceMethod(interp, (Tcl_Object) oPtr, namePtr,
+	TclNewInstanceMethod(interp, (Tcl_Object) oPtr, namePtr,
 		mPtr->flags & PUBLIC_METHOD, mPtr->typePtr, mPtr->clientData);
     }
     return TCL_OK;
@@ -2275,7 +2275,7 @@ CloneClassMethod(
     Method *m2Ptr;
 
     if (mPtr->typePtr == NULL) {
-	m2Ptr = (Method *) Tcl_NewMethod(interp, (Tcl_Class) clsPtr,
+	m2Ptr = (Method *) TclNewMethod(interp, (Tcl_Class) clsPtr,
 		namePtr, mPtr->flags & PUBLIC_METHOD, NULL, NULL);
     } else if (mPtr->typePtr->cloneProc) {
 	ClientData newClientData;
@@ -2284,11 +2284,11 @@ CloneClassMethod(
 		&newClientData) != TCL_OK) {
 	    return TCL_ERROR;
 	}
-	m2Ptr = (Method *) Tcl_NewMethod(interp, (Tcl_Class) clsPtr,
+	m2Ptr = (Method *) TclNewMethod(interp, (Tcl_Class) clsPtr,
 		namePtr, mPtr->flags & PUBLIC_METHOD, mPtr->typePtr,
 		newClientData);
     } else {
-	m2Ptr = (Method *) Tcl_NewMethod(interp, (Tcl_Class) clsPtr,
+	m2Ptr = (Method *) TclNewMethod(interp, (Tcl_Class) clsPtr,
 		namePtr, mPtr->flags & PUBLIC_METHOD, mPtr->typePtr,
 		mPtr->clientData);
     }
diff --git a/generic/tclOO.decls b/generic/tclOO.decls
index c6ffccd..c933872 100644
--- a/generic/tclOO.decls
+++ b/generic/tclOO.decls
@@ -135,6 +135,20 @@ declare 30 {
 declare 31 {
     Tcl_Obj *Tcl_GetObjectClassName(Tcl_Interp *interp, Tcl_Object object)
 }
+declare 32 {
+    int Tcl_MethodIsType2(Tcl_Method method, const Tcl_MethodType2 *typePtr,
+	    void **clientDataPtr)
+}
+declare 33 {
+    Tcl_Method Tcl_NewInstanceMethod2(Tcl_Interp *interp, Tcl_Object object,
+	    Tcl_Obj *nameObj, int flags, const Tcl_MethodType2 *typePtr,
+	    void *clientData)
+}
+declare 34 {
+    Tcl_Method Tcl_NewMethod2(Tcl_Interp *interp, Tcl_Class cls,
+	    Tcl_Obj *nameObj, int flags, const Tcl_MethodType2 *typePtr,
+	    void *clientData)
+}
 
 ######################################################################
 # Private API, exposed to support advanced OO systems that plug in on top of
diff --git a/generic/tclOO.h b/generic/tclOO.h
index 4a3398f..6f18491 100644
--- a/generic/tclOO.h
+++ b/generic/tclOO.h
@@ -24,8 +24,8 @@
  * win/tclooConfig.sh
  */
 
-#define TCLOO_VERSION "1.2.0"
-#define TCLOO_PATCHLEVEL TCLOO_VERSION
+#define TCLOO_VERSION "1.3"
+#define TCLOO_PATCHLEVEL TCLOO_VERSION ".0"
 
 #include "tcl.h"
 
@@ -40,7 +40,7 @@ extern "C" {
 extern const char *TclOOInitializeStubs(
 	Tcl_Interp *, const char *version);
 #define Tcl_OOInitStubs(interp) \
-    TclOOInitializeStubs((interp), TCLOO_VERSION)
+    TclOOInitializeStubs((interp), TCLOO_PATCHLEVEL)
 #ifndef USE_TCL_STUBS
 #   define TclOOInitializeStubs(interp, version) (TCLOO_PATCHLEVEL)
 #endif
@@ -62,6 +62,8 @@ typedef struct Tcl_ObjectContext_ *Tcl_ObjectContext;
 
 typedef int (Tcl_MethodCallProc)(void *clientData, Tcl_Interp *interp,
 	Tcl_ObjectContext objectContext, int objc, Tcl_Obj *const *objv);
+typedef int (Tcl_MethodCallProc2)(void *clientData, Tcl_Interp *interp,
+	Tcl_ObjectContext objectContext, size_t objc, Tcl_Obj *const *objv);
 typedef void (Tcl_MethodDeleteProc)(void *clientData);
 typedef int (Tcl_CloneProc)(Tcl_Interp *interp, void *oldClientData,
 	void **newClientData);
@@ -77,7 +79,7 @@ typedef int (Tcl_ObjectMapMethodNameProc)(Tcl_Interp *interp,
 
 typedef struct {
     int version;		/* Structure version field. Always to be equal
-				 * to TCL_OO_METHOD_VERSION_CURRENT in
+				 * to TCL_OO_METHOD_VERSION_(1|CURRENT) in
 				 * declarations. */
     const char *name;		/* Name of this type of method, mostly for
 				 * debugging purposes. */
@@ -92,12 +94,31 @@ typedef struct {
 				 * be copied directly. */
 } Tcl_MethodType;
 
+typedef struct {
+    int version;		/* Structure version field. Always to be equal
+				 * to TCL_OO_METHOD_VERSION_2 in
+				 * declarations. */
+    const char *name;		/* Name of this type of method, mostly for
+				 * debugging purposes. */
+    Tcl_MethodCallProc2 *callProc;
+				/* How to invoke this method. */
+    Tcl_MethodDeleteProc *deleteProc;
+				/* How to delete this method's type-specific
+				 * data, or NULL if the type-specific data
+				 * does not need deleting. */
+    Tcl_CloneProc *cloneProc;	/* How to copy this method's type-specific
+				 * data, or NULL if the type-specific data can
+				 * be copied directly. */
+} Tcl_MethodType2;
+
 /*
  * The correct value for the version field of the Tcl_MethodType structure.
  * This allows new versions of the structure to be introduced without breaking
  * binary compatibility.
  */
 
+#define TCL_OO_METHOD_VERSION_1 1
+#define TCL_OO_METHOD_VERSION_2 2
 #define TCL_OO_METHOD_VERSION_CURRENT 1
 
 /*
diff --git a/generic/tclOOCall.c b/generic/tclOOCall.c
index d265c1a..a9ed6bf 100644
--- a/generic/tclOOCall.c
+++ b/generic/tclOOCall.c
@@ -369,7 +369,11 @@ TclOOInvokeContext(
      * Run the method implementation.
      */
 
-    return mPtr->typePtr->callProc(mPtr->clientData, interp,
+    if (mPtr->typePtr->version < TCL_OO_METHOD_VERSION_2) {
+	return (mPtr->typePtr->callProc)(mPtr->clientData, interp,
+		(Tcl_ObjectContext) contextPtr, objc, objv);
+    }
+    return ((Tcl_MethodCallProc2 *)(void *)(mPtr->typePtr->callProc))(mPtr->clientData, interp,
 	    (Tcl_ObjectContext) contextPtr, objc, objv);
 }
 
diff --git a/generic/tclOODecls.h b/generic/tclOODecls.h
index 6ba5d14..13e07ec 100644
--- a/generic/tclOODecls.h
+++ b/generic/tclOODecls.h
@@ -123,6 +123,20 @@ TCLAPI Tcl_Class	Tcl_GetClassOfObject(Tcl_Object object);
 /* 31 */
 TCLAPI Tcl_Obj *	Tcl_GetObjectClassName(Tcl_Interp *interp,
 				Tcl_Object object);
+/* 32 */
+TCLAPI int		Tcl_MethodIsType2(Tcl_Method method,
+				const Tcl_MethodType2 *typePtr,
+				void **clientDataPtr);
+/* 33 */
+TCLAPI Tcl_Method	Tcl_NewInstanceMethod2(Tcl_Interp *interp,
+				Tcl_Object object, Tcl_Obj *nameObj,
+				int flags, const Tcl_MethodType2 *typePtr,
+				void *clientData);
+/* 34 */
+TCLAPI Tcl_Method	Tcl_NewMethod2(Tcl_Interp *interp, Tcl_Class cls,
+				Tcl_Obj *nameObj, int flags,
+				const Tcl_MethodType2 *typePtr,
+				void *clientData);
 
 typedef struct {
     const struct TclOOIntStubs *tclOOIntStubs;
@@ -164,6 +178,9 @@ typedef struct TclOOStubs {
     int (*tcl_MethodIsPrivate) (Tcl_Method method); /* 29 */
     Tcl_Class (*tcl_GetClassOfObject) (Tcl_Object object); /* 30 */
     Tcl_Obj * (*tcl_GetObjectClassName) (Tcl_Interp *interp, Tcl_Object object); /* 31 */
+    int (*tcl_MethodIsType2) (Tcl_Method method, const Tcl_MethodType2 *typePtr, void **clientDataPtr); /* 32 */
+    Tcl_Method (*tcl_NewInstanceMethod2) (Tcl_Interp *interp, Tcl_Object object, Tcl_Obj *nameObj, int flags, const Tcl_MethodType2 *typePtr, void *clientData); /* 33 */
+    Tcl_Method (*tcl_NewMethod2) (Tcl_Interp *interp, Tcl_Class cls, Tcl_Obj *nameObj, int flags, const Tcl_MethodType2 *typePtr, void *clientData); /* 34 */
 } TclOOStubs;
 
 extern const TclOOStubs *tclOOStubsPtr;
@@ -242,6 +259,12 @@ extern const TclOOStubs *tclOOStubsPtr;
 	(tclOOStubsPtr->tcl_GetClassOfObject) /* 30 */
 #define Tcl_GetObjectClassName \
 	(tclOOStubsPtr->tcl_GetObjectClassName) /* 31 */
+#define Tcl_MethodIsType2 \
+	(tclOOStubsPtr->tcl_MethodIsType2) /* 32 */
+#define Tcl_NewInstanceMethod2 \
+	(tclOOStubsPtr->tcl_NewInstanceMethod2) /* 33 */
+#define Tcl_NewMethod2 \
+	(tclOOStubsPtr->tcl_NewMethod2) /* 34 */
 
 #endif /* defined(USE_TCLOO_STUBS) */
 
diff --git a/generic/tclOODefineCmds.c b/generic/tclOODefineCmds.c
index 42c6637..686fd00 100644
--- a/generic/tclOODefineCmds.c
+++ b/generic/tclOODefineCmds.c
@@ -2286,12 +2286,12 @@ TclOODefineSlots(
 	if (slotObject == NULL) {
 	    continue;
 	}
-	Tcl_NewInstanceMethod(fPtr->interp, slotObject, getName, 0,
+	TclNewInstanceMethod(fPtr->interp, slotObject, getName, 0,
 		&slotInfoPtr->getterType, NULL);
-	Tcl_NewInstanceMethod(fPtr->interp, slotObject, setName, 0,
+	TclNewInstanceMethod(fPtr->interp, slotObject, setName, 0,
 		&slotInfoPtr->setterType, NULL);
 	if (slotInfoPtr->resolverType.callProc) {
-	    Tcl_NewInstanceMethod(fPtr->interp, slotObject, resolveName, 0,
+	    TclNewInstanceMethod(fPtr->interp, slotObject, resolveName, 0,
 		    &slotInfoPtr->resolverType, NULL);
 	}
     }
diff --git a/generic/tclOOInt.h b/generic/tclOOInt.h
index 9488271..725c4ce 100644
--- a/generic/tclOOInt.h
+++ b/generic/tclOOInt.h
@@ -235,14 +235,14 @@ typedef struct Object {
 				 * other spots). */
 #define FORCE_UNKNOWN 0x10000	/* States that we are *really* looking up the
 				 * unknown method handler at that point. */
-#define HAS_PRIVATE_METHODS 0x20000
-				/* Object/class has (or had) private methods,
-				 * and so shouldn't be cached so
-				 * aggressively. */
-#define DONT_DELETE 0x40000	/* Inhibit deletion of this object. Used
+#define DONT_DELETE 0x20000	/* Inhibit deletion of this object. Used
 				 * during fundamental object type mutation to
 				 * make sure that the object actually survives
 				 * to the end of the operation. */
+#define HAS_PRIVATE_METHODS 0x40000
+				/* Object/class has (or had) private methods,
+				 * and so shouldn't be cached so
+				 * aggressively. */
 
 /*
  * And the definition of a class. Note that every class also has an associated
@@ -492,6 +492,17 @@ MODULE_SCOPE void	TclOOAddToMixinSubs(Class *subPtr, Class *mixinPtr);
 MODULE_SCOPE void	TclOOAddToSubclasses(Class *subPtr, Class *superPtr);
 MODULE_SCOPE Class *	TclOOAllocClass(Tcl_Interp *interp,
 			    Object *useThisObj);
+MODULE_SCOPE int    TclMethodIsType(Tcl_Method method,
+                        const Tcl_MethodType *typePtr,
+                        void **clientDataPtr);
+MODULE_SCOPE Tcl_Method TclNewInstanceMethod(Tcl_Interp *interp,
+                        Tcl_Object object, Tcl_Obj *nameObj,
+                        int flags, const Tcl_MethodType *typePtr,
+                        void *clientData);
+MODULE_SCOPE Tcl_Method TclNewMethod(Tcl_Interp *interp, Tcl_Class cls,
+                        Tcl_Obj *nameObj, int flags,
+                        const Tcl_MethodType *typePtr,
+                        void *clientData);
 MODULE_SCOPE int	TclNRNewObjectInstance(Tcl_Interp *interp,
 			    Tcl_Class cls, const char *nameStr,
 			    const char *nsNameStr, int objc,
diff --git a/generic/tclOOMethod.c b/generic/tclOOMethod.c
index ae1f3bd..73368e4 100644
--- a/generic/tclOOMethod.c
+++ b/generic/tclOOMethod.c
@@ -126,7 +126,7 @@ static const Tcl_MethodType fwdMethodType = {
  */
 
 Tcl_Method
-Tcl_NewInstanceMethod(
+TclNewInstanceMethod(
     TCL_UNUSED(Tcl_Interp *),
     Tcl_Object object,		/* The object that has the method attached to
 				 * it. */
@@ -187,6 +187,50 @@ Tcl_NewInstanceMethod(
     oPtr->epoch++;
     return (Tcl_Method) mPtr;
 }
+Tcl_Method
+Tcl_NewInstanceMethod(
+    TCL_UNUSED(Tcl_Interp *),
+    Tcl_Object object,		/* The object that has the method attached to
+				 * it. */
+    Tcl_Obj *nameObj,		/* The name of the method. May be NULL; if so,
+				 * up to caller to manage storage (e.g., when
+				 * it is a constructor or destructor). */
+    int flags,			/* Whether this is a public method. */
+    const Tcl_MethodType *typePtr,
+				/* The type of method this is, which defines
+				 * how to invoke, delete and clone the
+				 * method. */
+    void *clientData)		/* Some data associated with the particular
+				 * method to be created. */
+{
+    if (typePtr->version > TCL_OO_METHOD_VERSION_1) {
+	Tcl_Panic("%s: Wrong version in typePtr->version, should be TCL_OO_METHOD_VERSION_1", "Tcl_NewInstanceMethod");
+    }
+    return TclNewInstanceMethod(NULL, object, nameObj, flags,
+	    (const Tcl_MethodType *)typePtr, clientData);
+}
+Tcl_Method
+Tcl_NewInstanceMethod2(
+    TCL_UNUSED(Tcl_Interp *),
+    Tcl_Object object,		/* The object that has the method attached to
+				 * it. */
+    Tcl_Obj *nameObj,		/* The name of the method. May be NULL; if so,
+				 * up to caller to manage storage (e.g., when
+				 * it is a constructor or destructor). */
+    int flags,			/* Whether this is a public method. */
+    const Tcl_MethodType2 *typePtr,
+				/* The type of method this is, which defines
+				 * how to invoke, delete and clone the
+				 * method. */
+    void *clientData)		/* Some data associated with the particular
+				 * method to be created. */
+{
+    if (typePtr->version < TCL_OO_METHOD_VERSION_2) {
+	Tcl_Panic("%s: Wrong version in typePtr->version, should be TCL_OO_METHOD_VERSION_2", "Tcl_NewInstanceMethod2");
+    }
+    return TclNewInstanceMethod(NULL, object, nameObj, flags,
+	    (const Tcl_MethodType *)typePtr, clientData);
+}
 
 /*
  * ----------------------------------------------------------------------
@@ -199,7 +243,7 @@ Tcl_NewInstanceMethod(
  */
 
 Tcl_Method
-Tcl_NewMethod(
+TclNewMethod(
     TCL_UNUSED(Tcl_Interp *),
     Tcl_Class cls,		/* The class to attach the method to. */
     Tcl_Obj *nameObj,		/* The name of the object. May be NULL (e.g.,
@@ -255,6 +299,48 @@ Tcl_NewMethod(
 
     return (Tcl_Method) mPtr;
 }
+
+Tcl_Method
+Tcl_NewMethod(
+    TCL_UNUSED(Tcl_Interp *),
+    Tcl_Class cls,		/* The class to attach the method to. */
+    Tcl_Obj *nameObj,		/* The name of the object. May be NULL (e.g.,
+				 * for constructors or destructors); if so, up
+				 * to caller to manage storage. */
+    int flags,			/* Whether this is a public method. */
+    const Tcl_MethodType *typePtr,
+				/* The type of method this is, which defines
+				 * how to invoke, delete and clone the
+				 * method. */
+    void *clientData)		/* Some data associated with the particular
+				 * method to be created. */
+{
+    if (typePtr->version > TCL_OO_METHOD_VERSION_1) {
+	Tcl_Panic("%s: Wrong version in typePtr->version, should be TCL_OO_METHOD_VERSION_1", "Tcl_NewMethod");
+    }
+    return TclNewMethod(NULL, cls, nameObj, flags, typePtr, clientData);
+}
+
+Tcl_Method
+Tcl_NewMethod2(
+    TCL_UNUSED(Tcl_Interp *),
+    Tcl_Class cls,		/* The class to attach the method to. */
+    Tcl_Obj *nameObj,		/* The name of the object. May be NULL (e.g.,
+				 * for constructors or destructors); if so, up
+				 * to caller to manage storage. */
+    int flags,			/* Whether this is a public method. */
+    const Tcl_MethodType2 *typePtr,
+				/* The type of method this is, which defines
+				 * how to invoke, delete and clone the
+				 * method. */
+    void *clientData)		/* Some data associated with the particular
+				 * method to be created. */
+{
+    if (typePtr->version < TCL_OO_METHOD_VERSION_2) {
+	Tcl_Panic("%s: Wrong version in typePtr->version, should be TCL_OO_METHOD_VERSION_2", "Tcl_NewMethod2");
+    }
+    return TclNewMethod(NULL, cls, nameObj, flags, (const Tcl_MethodType *)typePtr, clientData);
+}
 
 /*
  * ----------------------------------------------------------------------
@@ -304,7 +390,7 @@ TclOONewBasicMethod(
     Tcl_Obj *namePtr = Tcl_NewStringObj(dcm->name, -1);
 
     Tcl_IncrRefCount(namePtr);
-    Tcl_NewMethod(interp, (Tcl_Class) clsPtr, namePtr,
+    TclNewMethod(interp, (Tcl_Class) clsPtr, namePtr,
 	    (dcm->isPublic ? PUBLIC_METHOD : 0), &dcm->definition, NULL);
     Tcl_DecrRefCount(namePtr);
 }
@@ -529,7 +615,7 @@ TclOOMakeProcInstanceMethod(
 	}
     }
 
-    return Tcl_NewInstanceMethod(interp, (Tcl_Object) oPtr, nameObj, flags,
+    return TclNewInstanceMethod(interp, (Tcl_Object) oPtr, nameObj, flags,
 	    typePtr, clientData);
 }
 
@@ -642,7 +728,7 @@ TclOOMakeProcMethod(
 	}
     }
 
-    return Tcl_NewMethod(interp, (Tcl_Class) clsPtr, nameObj, flags, typePtr,
+    return TclNewMethod(interp, (Tcl_Class) clsPtr, nameObj, flags, typePtr,
 	    clientData);
 }
 
@@ -1402,7 +1488,7 @@ TclOONewForwardInstanceMethod(
     fmPtr = (ForwardMethod *)ckalloc(sizeof(ForwardMethod));
     fmPtr->prefixObj = prefixObj;
     Tcl_IncrRefCount(prefixObj);
-    return (Method *) Tcl_NewInstanceMethod(interp, (Tcl_Object) oPtr,
+    return (Method *) TclNewInstanceMethod(interp, (Tcl_Object) oPtr,
 	    nameObj, flags, &fwdMethodType, fmPtr);
 }
 
@@ -1441,7 +1527,7 @@ TclOONewForwardMethod(
     fmPtr = (ForwardMethod *)ckalloc(sizeof(ForwardMethod));
     fmPtr->prefixObj = prefixObj;
     Tcl_IncrRefCount(prefixObj);
-    return (Method *) Tcl_NewMethod(interp, (Tcl_Class) clsPtr, nameObj,
+    return (Method *) TclNewMethod(interp, (Tcl_Class) clsPtr, nameObj,
 	    flags, &fwdMethodType, fmPtr);
 }
 
@@ -1672,6 +1758,23 @@ Tcl_MethodName(
 }
 
 int
+TclMethodIsType(
+    Tcl_Method method,
+    const Tcl_MethodType *typePtr,
+    void **clientDataPtr)
+{
+    Method *mPtr = (Method *) method;
+
+    if (mPtr->typePtr == typePtr) {
+	if (clientDataPtr != NULL) {
+	    *clientDataPtr = mPtr->clientData;
+	}
+	return 1;
+    }
+    return 0;
+}
+
+int
 Tcl_MethodIsType(
     Tcl_Method method,
     const Tcl_MethodType *typePtr,
@@ -1679,6 +1782,9 @@ Tcl_MethodIsType(
 {
     Method *mPtr = (Method *) method;
 
+    if (typePtr->version > TCL_OO_METHOD_VERSION_1) {
+	Tcl_Panic("%s: Wrong version in typePtr->version, should be TCL_OO_METHOD_VERSION_1", "Tcl_MethodIsType");
+    }
     if (mPtr->typePtr == typePtr) {
 	if (clientDataPtr != NULL) {
 	    *clientDataPtr = mPtr->clientData;
@@ -1689,6 +1795,26 @@ Tcl_MethodIsType(
 }
 
 int
+Tcl_MethodIsType2(
+    Tcl_Method method,
+    const Tcl_MethodType2 *typePtr,
+    void **clientDataPtr)
+{
+    Method *mPtr = (Method *) method;
+
+    if (typePtr->version < TCL_OO_METHOD_VERSION_2) {
+	Tcl_Panic("%s: Wrong version in typePtr->version, should be TCL_OO_METHOD_VERSION_2", "Tcl_MethodIsType2");
+    }
+    if (mPtr->typePtr == (const Tcl_MethodType *)typePtr) {
+	if (clientDataPtr != NULL) {
+	    *clientDataPtr = mPtr->clientData;
+	}
+	return 1;
+    }
+    return 0;
+}
+
+int
 Tcl_MethodIsPublic(
     Tcl_Method method)
 {
diff --git a/generic/tclOOStubInit.c b/generic/tclOOStubInit.c
index b9034f0..7b653cb 100644
--- a/generic/tclOOStubInit.c
+++ b/generic/tclOOStubInit.c
@@ -76,6 +76,9 @@ const TclOOStubs tclOOStubs = {
     Tcl_MethodIsPrivate, /* 29 */
     Tcl_GetClassOfObject, /* 30 */
     Tcl_GetObjectClassName, /* 31 */
+    Tcl_MethodIsType2, /* 32 */
+    Tcl_NewInstanceMethod2, /* 33 */
+    Tcl_NewMethod2, /* 34 */
 };
 
 /* !END!: Do not edit above this line. */
diff --git a/generic/tclProc.c b/generic/tclProc.c
index e6b1372..059e751 100644
--- a/generic/tclProc.c
+++ b/generic/tclProc.c
@@ -148,6 +148,7 @@ static const Tcl_ObjType lambdaType = {
  *----------------------------------------------------------------------
  */
 
+#undef TclObjInterpProc
 int
 Tcl_ProcObjCmd(
     TCL_UNUSED(ClientData),
@@ -1645,6 +1646,7 @@ TclPushProcCallFrame(
  *----------------------------------------------------------------------
  */
 
+#undef TclObjInterpProc
 int
 TclObjInterpProc(
     ClientData clientData,	/* Record describing procedure to be
@@ -2163,7 +2165,7 @@ TclProcCleanupProc(
     if (bodyPtr != NULL) {
 	/* procPtr is stored in body's ByteCode, so ensure to reset it. */
 	ByteCode *codePtr;
-	
+
 	ByteCodeGetInternalRep(bodyPtr, &tclByteCodeType, codePtr);
 	if (codePtr != NULL && codePtr->procPtr == procPtr) {
 	    codePtr->procPtr = NULL;
diff --git a/generic/tclStubInit.c b/generic/tclStubInit.c
index 2b7952d..ae00b04 100644
--- a/generic/tclStubInit.c
+++ b/generic/tclStubInit.c
@@ -83,6 +83,7 @@
 #undef Tcl_UtfAtIndex
 #undef Tcl_GetRange
 #undef Tcl_GetUniChar
+#undef TclObjInterpProc
 
 #if defined(_WIN32) || defined(__CYGWIN__)
 #define TclWinConvertWSAError (void (*)(DWORD))(void *)Tcl_WinConvertError
@@ -1118,7 +1119,9 @@ static const TclIntStubs tclIntStubs = {
     TclPtrUnsetVar, /* 256 */
     TclStaticLibrary, /* 257 */
     TclpCreateTemporaryDirectory, /* 258 */
-    TclUnusedStubEntry, /* 259 */
+    0, /* 259 */
+    TclListTestObj, /* 260 */
+    TclListObjValidate, /* 261 */
 };
 
 static const TclIntPlatStubs tclIntPlatStubs = {
@@ -2034,6 +2037,12 @@ const TclStubs tclStubs = {
     TclUtfAtIndex, /* 671 */
     TclGetRange, /* 672 */
     TclGetUniChar, /* 673 */
+    0, /* 674 */
+    0, /* 675 */
+    Tcl_CreateObjCommand2, /* 676 */
+    Tcl_CreateObjTrace2, /* 677 */
+    Tcl_NRCreateCommand2, /* 678 */
+    Tcl_NRCallObjProc2, /* 679 */
 };
 
 /* !END!: Do not edit above this line. */
diff --git a/generic/tclTest.c b/generic/tclTest.c
index ed5f34b..f6515c1 100644
--- a/generic/tclTest.c
+++ b/generic/tclTest.c
@@ -61,6 +61,21 @@ static Tcl_DString delString;
 static Tcl_Interp *delInterp;
 
 /*
+ * One of the following structures exists for each command created by the
+ * "testcmdtoken" command.
+ */
+
+typedef struct TestCommandTokenRef {
+    int id;			/* Identifier for this reference. */
+    Tcl_Command token;		/* Tcl's token for the command. */
+    struct TestCommandTokenRef *nextPtr;
+				/* Next in list of references. */
+} TestCommandTokenRef;
+
+static TestCommandTokenRef *firstCommandTokenRef = NULL;
+static int nextCommandTokenRefId = 1;
+
+/*
  * One of the following structures exists for each asynchronous handler
  * created by the "testasync" command".
  */
@@ -82,8 +97,7 @@ typedef struct TcpState TcpState;
 
 struct TcpState {
     Tcl_Channel channel;	/* Channel associated with this socket. */
-    int testFlags;              /* bit field for tests. Is set by testsocket
-                                 * test procedure */
+    int flags;			/* ORed combination of various bitfields. */
 };
 
 TCL_DECLARE_MUTEX(asyncTestMutex)
@@ -258,6 +272,7 @@ static Tcl_ObjCmdProc	TestgetvarfullnameCmd;
 static Tcl_CmdProc	TestinterpdeleteCmd;
 static Tcl_CmdProc	TestlinkCmd;
 static Tcl_ObjCmdProc	TestlinkarrayCmd;
+static Tcl_ObjCmdProc	TestlistrepCmd;
 static Tcl_ObjCmdProc	TestlocaleCmd;
 static Tcl_CmdProc	TestmainthreadCmd;
 static Tcl_CmdProc	TestsetmainloopCmd;
@@ -544,6 +559,12 @@ Tcltest_Init(
     }
 
     if (Tcl_GetCommandInfo(interp, "::tcl::build-info", &info)) {
+#if TCL_MAJOR_VERSION > 8
+	if (info.isNativeObjectProc == 2) {
+	    Tcl_CreateObjCommand2(interp, "::tcl::test::build-info",
+		    info.objProc2, (void *)version, NULL);
+    } else
+#endif
 	Tcl_CreateObjCommand(interp, "::tcl::test::build-info",
 		info.objProc, (void *)version, NULL);
     }
@@ -641,6 +662,7 @@ Tcltest_Init(
 	    NULL, NULL);
     Tcl_CreateCommand(interp, "testlink", TestlinkCmd, NULL, NULL);
     Tcl_CreateObjCommand(interp, "testlinkarray", TestlinkarrayCmd, NULL, NULL);
+    Tcl_CreateObjCommand(interp, "testlistrep", TestlistrepCmd, NULL, NULL);
     Tcl_CreateObjCommand(interp, "testlocale", TestlocaleCmd, NULL,
 	    NULL);
     Tcl_CreateCommand(interp, "testpanic", TestpanicCmd, NULL, NULL);
@@ -755,7 +777,7 @@ Tcltest_Init(
 		return TCL_ERROR;
 	    }
 	    case 3:
-		if (objc-1) {
+		if (objc > 1) {
 		    Tcl_SetVar2Ex(interp, "tcl_rcFileName", NULL, objv[1],
 			    TCL_GLOBAL_ONLY);
 		}
@@ -800,6 +822,12 @@ Tcltest_SafeInit(
 	return TCL_ERROR;
     }
     if (Tcl_GetCommandInfo(interp, "::tcl::build-info", &info)) {
+#if TCL_MAJOR_VERSION > 8
+	if (info.isNativeObjectProc == 2) {
+	    Tcl_CreateObjCommand2(interp, "::tcl::test::build-info",
+		    info.objProc2, (void *)version, NULL);
+    } else
+#endif
 	Tcl_CreateObjCommand(interp, "::tcl::test::build-info",
 		info.objProc, (void *)version, NULL);
     }
@@ -910,7 +938,7 @@ TestasyncCmd(
 		break;
 	    }
 	}
-	Tcl_SetObjResult(interp, Tcl_NewStringObj(argv[3], -1));
+	Tcl_SetObjResult(interp, Tcl_NewStringObj(argv[3], TCL_INDEX_NONE));
 	Tcl_MutexUnlock(&asyncTestMutex);
 	return code;
     } else if (strcmp(argv[1], "marklater") == 0) {
@@ -978,7 +1006,7 @@ AsyncHandlerProc(
     listArgv[3] = NULL;
     cmd = Tcl_Merge(3, listArgv);
     if (interp != NULL) {
-	code = Tcl_EvalEx(interp, cmd, -1, 0);
+	code = Tcl_EvalEx(interp, cmd, TCL_INDEX_NONE, 0);
     } else {
 	/*
 	 * this should not happen, but by definition of how async handlers are
@@ -1159,8 +1187,8 @@ CmdDelProc1(
     void *clientData)	/* String to save. */
 {
     Tcl_DStringInit(&delString);
-    Tcl_DStringAppend(&delString, "CmdDelProc1 ", -1);
-    Tcl_DStringAppend(&delString, (char *) clientData, -1);
+    Tcl_DStringAppend(&delString, "CmdDelProc1 ", TCL_INDEX_NONE);
+    Tcl_DStringAppend(&delString, (char *) clientData, TCL_INDEX_NONE);
 }
 
 static void
@@ -1168,8 +1196,8 @@ CmdDelProc2(
     void *clientData)	/* String to save. */
 {
     Tcl_DStringInit(&delString);
-    Tcl_DStringAppend(&delString, "CmdDelProc2 ", -1);
-    Tcl_DStringAppend(&delString, (char *) clientData, -1);
+    Tcl_DStringAppend(&delString, "CmdDelProc2 ", TCL_INDEX_NONE);
+    Tcl_DStringAppend(&delString, (char *) clientData, TCL_INDEX_NONE);
 }
 
 /*
@@ -1196,9 +1224,9 @@ TestcmdtokenCmd(
     int argc,			/* Number of arguments. */
     const char **argv)		/* Argument strings. */
 {
-    Tcl_Command token;
-    int *l;
+    TestCommandTokenRef *refPtr;
     char buf[30];
+    int id;
 
     if (argc != 3) {
 	Tcl_AppendResult(interp, "wrong # args: should be \"", argv[0],
@@ -1206,24 +1234,42 @@ TestcmdtokenCmd(
 	return TCL_ERROR;
     }
     if (strcmp(argv[1], "create") == 0) {
-	token = Tcl_CreateCommand(interp, argv[2], CmdProc1,
+	refPtr = (TestCommandTokenRef *)Tcl_Alloc(sizeof(TestCommandTokenRef));
+	refPtr->token = Tcl_CreateCommand(interp, argv[2], CmdProc1,
 		(void *) "original", NULL);
-	sprintf(buf, "%p", (void *)token);
+	refPtr->id = nextCommandTokenRefId;
+	nextCommandTokenRefId++;
+	refPtr->nextPtr = firstCommandTokenRef;
+	firstCommandTokenRef = refPtr;
+	sprintf(buf, "%d", refPtr->id);
 	Tcl_AppendResult(interp, buf, NULL);
     } else if (strcmp(argv[1], "name") == 0) {
 	Tcl_Obj *objPtr;
 
-	if (sscanf(argv[2], "%p", &l) != 1) {
+	if (sscanf(argv[2], "%d", &id) != 1) {
+	    Tcl_AppendResult(interp, "bad command token \"", argv[2],
+		    "\"", NULL);
+	    return TCL_ERROR;
+	}
+
+	for (refPtr = firstCommandTokenRef; refPtr != NULL;
+		refPtr = refPtr->nextPtr) {
+	    if (refPtr->id == id) {
+		break;
+	    }
+	}
+
+	if (refPtr == NULL) {
 	    Tcl_AppendResult(interp, "bad command token \"", argv[2],
 		    "\"", NULL);
 	    return TCL_ERROR;
 	}
 
 	objPtr = Tcl_NewObj();
-	Tcl_GetCommandFullName(interp, (Tcl_Command) l, objPtr);
+	Tcl_GetCommandFullName(interp, refPtr->token, objPtr);
 
 	Tcl_AppendElement(interp,
-		Tcl_GetCommandName(interp, (Tcl_Command) l));
+		Tcl_GetCommandName(interp, refPtr->token));
 	Tcl_AppendElement(interp, Tcl_GetString(objPtr));
 	Tcl_DecrRefCount(objPtr);
     } else {
@@ -1271,7 +1317,7 @@ TestcmdtraceCmd(
     if (strcmp(argv[1], "tracetest") == 0) {
 	Tcl_DStringInit(&buffer);
 	cmdTrace = Tcl_CreateTrace(interp, 50000, CmdTraceProc, &buffer);
-	result = Tcl_EvalEx(interp, argv[2], -1, 0);
+	result = Tcl_EvalEx(interp, argv[2], TCL_INDEX_NONE, 0);
 	if (result == TCL_OK) {
 	    Tcl_ResetResult(interp);
 	    Tcl_AppendResult(interp, Tcl_DStringValue(&buffer), NULL);
@@ -1287,13 +1333,13 @@ TestcmdtraceCmd(
 	 */
 
 	cmdTrace = Tcl_CreateTrace(interp, 50000, CmdTraceDeleteProc, NULL);
-	Tcl_EvalEx(interp, argv[2], -1, 0);
+	Tcl_EvalEx(interp, argv[2], TCL_INDEX_NONE, 0);
     } else if (strcmp(argv[1], "leveltest") == 0) {
 	Interp *iPtr = (Interp *) interp;
 	Tcl_DStringInit(&buffer);
 	cmdTrace = Tcl_CreateTrace(interp, iPtr->numLevels + 4, CmdTraceProc,
 		&buffer);
-	result = Tcl_EvalEx(interp, argv[2], -1, 0);
+	result = Tcl_EvalEx(interp, argv[2], TCL_INDEX_NONE, 0);
 	if (result == TCL_OK) {
 	    Tcl_ResetResult(interp);
 	    Tcl_AppendResult(interp, Tcl_DStringValue(&buffer), NULL);
@@ -1311,7 +1357,7 @@ TestcmdtraceCmd(
 	cmdTrace = Tcl_CreateObjTrace(interp, 50000,
 		TCL_ALLOW_INLINE_COMPILATION, ObjTraceProc,
 		&deleteCalled, ObjTraceDeleteProc);
-	result = Tcl_EvalEx(interp, argv[2], -1, 0);
+	result = Tcl_EvalEx(interp, argv[2], TCL_INDEX_NONE, 0);
 	Tcl_DeleteTrace(interp, cmdTrace);
 	if (!deleteCalled) {
 	    Tcl_AppendResult(interp, "Delete wasn't called", NULL);
@@ -1325,7 +1371,7 @@ TestcmdtraceCmd(
 	Tcl_DStringInit(&buffer);
 	t1 = Tcl_CreateTrace(interp, 1, CmdTraceProc, &buffer);
 	t2 = Tcl_CreateTrace(interp, 50000, CmdTraceProc, &buffer);
-	result = Tcl_EvalEx(interp, argv[2], -1, 0);
+	result = Tcl_EvalEx(interp, argv[2], TCL_INDEX_NONE, 0);
 	if (result == TCL_OK) {
 	    Tcl_ResetResult(interp);
 	    Tcl_AppendResult(interp, Tcl_DStringValue(&buffer), NULL);
@@ -1400,7 +1446,7 @@ ObjTraceProc(
     const char *word = Tcl_GetString(objv[0]);
 
     if (!strcmp(word, "Error")) {
-	Tcl_SetObjResult(interp, Tcl_NewStringObj(command, -1));
+	Tcl_SetObjResult(interp, Tcl_NewStringObj(command, TCL_INDEX_NONE));
 	return TCL_ERROR;
     } else if (!strcmp(word, "Break")) {
 	return TCL_BREAK;
@@ -1649,7 +1695,7 @@ DelDeleteProc(
 {
     DelCmd *dPtr = (DelCmd *)clientData;
 
-    Tcl_EvalEx(dPtr->interp, dPtr->deleteCmd, -1, 0);
+    Tcl_EvalEx(dPtr->interp, dPtr->deleteCmd, TCL_INDEX_NONE, 0);
     Tcl_ResetResult(dPtr->interp);
     ckfree(dPtr->deleteCmd);
     ckfree(dPtr);
@@ -1764,7 +1810,7 @@ TestdoubledigitsObjCmd(
     type = types[type];
     if (objc > 4) {
 	if (strcmp(Tcl_GetString(objv[4]), "shorten")) {
-	    Tcl_SetObjResult(interp, Tcl_NewStringObj("bad flag", -1));
+	    Tcl_SetObjResult(interp, Tcl_NewStringObj("bad flag", TCL_INDEX_NONE));
 	    return TCL_ERROR;
 	}
 	type |= TCL_DD_SHORTEST;
@@ -2008,7 +2054,7 @@ EncodingToUtfProc(
     TclEncoding *encodingPtr;
 
     encodingPtr = (TclEncoding *) clientData;
-    Tcl_EvalEx(encodingPtr->interp, encodingPtr->toUtfCmd, -1, TCL_EVAL_GLOBAL);
+    Tcl_EvalEx(encodingPtr->interp, encodingPtr->toUtfCmd, TCL_INDEX_NONE, TCL_EVAL_GLOBAL);
 
     len = strlen(Tcl_GetStringResult(encodingPtr->interp));
     if (len > dstLen) {
@@ -2040,7 +2086,7 @@ EncodingFromUtfProc(
     TclEncoding *encodingPtr;
 
     encodingPtr = (TclEncoding *) clientData;
-    Tcl_EvalEx(encodingPtr->interp, encodingPtr->fromUtfCmd, -1, TCL_EVAL_GLOBAL);
+    Tcl_EvalEx(encodingPtr->interp, encodingPtr->fromUtfCmd, TCL_INDEX_NONE, TCL_EVAL_GLOBAL);
 
     len = strlen(Tcl_GetStringResult(encodingPtr->interp));
     if (len > dstLen) {
@@ -3079,7 +3125,7 @@ TestlinkCmd(
 	    }
 	}
 	if (argv[6][0] != 0) {
-	    tmp = Tcl_NewStringObj(argv[6], -1);
+	    tmp = Tcl_NewStringObj(argv[6], TCL_INDEX_NONE);
 	    if (Tcl_GetWideIntFromObj(interp, tmp, &wideVar) != TCL_OK) {
 		Tcl_DecrRefCount(tmp);
 		return TCL_ERROR;
@@ -3137,7 +3183,7 @@ TestlinkCmd(
 	}
 	if (argv[15][0]) {
 	    Tcl_WideInt w;
-	    tmp = Tcl_NewStringObj(argv[15], -1);
+	    tmp = Tcl_NewStringObj(argv[15], TCL_INDEX_NONE);
 	    if (Tcl_GetWideIntFromObj(interp, tmp, &w) != TCL_OK) {
 		Tcl_DecrRefCount(tmp);
 		return TCL_ERROR;
@@ -3187,7 +3233,7 @@ TestlinkCmd(
 	    Tcl_UpdateLinkedVar(interp, "string");
 	}
 	if (argv[6][0] != 0) {
-	    tmp = Tcl_NewStringObj(argv[6], -1);
+	    tmp = Tcl_NewStringObj(argv[6], TCL_INDEX_NONE);
 	    if (Tcl_GetWideIntFromObj(interp, tmp, &wideVar) != TCL_OK) {
 		Tcl_DecrRefCount(tmp);
 		return TCL_ERROR;
@@ -3254,7 +3300,7 @@ TestlinkCmd(
 	}
 	if (argv[15][0]) {
 	    Tcl_WideInt w;
-	    tmp = Tcl_NewStringObj(argv[15], -1);
+	    tmp = Tcl_NewStringObj(argv[15], TCL_INDEX_NONE);
 	    if (Tcl_GetWideIntFromObj(interp, tmp, &w) != TCL_OK) {
 		Tcl_DecrRefCount(tmp);
 		return TCL_ERROR;
@@ -3361,7 +3407,7 @@ TestlinkarrayCmd(
 	    return TCL_ERROR;
 	}
 	if (Tcl_GetIntFromObj(interp, objv[i++], &size) == TCL_ERROR) {
-	    Tcl_SetObjResult(interp, Tcl_NewStringObj("wrong size value", -1));
+	    Tcl_SetObjResult(interp, Tcl_NewStringObj("wrong size value", TCL_INDEX_NONE));
 	    return TCL_ERROR;
 	}
 	name = Tcl_GetString(objv[i++]);
@@ -3373,7 +3419,7 @@ TestlinkarrayCmd(
 	if (i < objc) {
 	    if (Tcl_GetWideIntFromObj(interp, objv[i], &addr) == TCL_ERROR) {
  		Tcl_SetObjResult(interp, Tcl_NewStringObj(
-			"wrong address value", -1));
+			"wrong address value", TCL_INDEX_NONE));
 		return TCL_ERROR;
 	    }
 	} else {
@@ -3392,6 +3438,158 @@ TestlinkarrayCmd(
 /*
  *----------------------------------------------------------------------
  *
+ * TestlistrepCmd --
+ *
+ *      This function is invoked to generate a list object with a specific
+ *	internal representation.
+ *
+ * Results:
+ *      A standard Tcl result.
+ *
+ * Side effects:
+ *	None.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static int
+TestlistrepCmd(
+    TCL_UNUSED(void *),
+    Tcl_Interp *interp,         /* Current interpreter. */
+    int objc,                   /* Number of arguments. */
+    Tcl_Obj *const objv[])      /* Argument objects. */
+{
+    /* Subcommands supported by this command */
+    const char* subcommands[] = {
+	"new",
+	"describe",
+	"config",
+	"validate",
+	NULL
+    };
+    enum {
+	LISTREP_NEW,
+	LISTREP_DESCRIBE,
+	LISTREP_CONFIG,
+	LISTREP_VALIDATE
+    } cmdIndex;
+    Tcl_Obj *resultObj = NULL;
+
+    if (objc < 2) {
+	Tcl_WrongNumArgs(interp, 1, objv, "command ?arg ...?");
+	return TCL_ERROR;
+    }
+    if (Tcl_GetIndexFromObj(
+	    interp, objv[1], subcommands, "command", 0, &cmdIndex)
+	!= TCL_OK) {
+	return TCL_ERROR;
+    }
+    switch (cmdIndex) {
+    case LISTREP_NEW:
+	if (objc < 3 || objc > 5) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "length ?leadSpace endSpace?");
+	    return TCL_ERROR;
+	} else {
+	    int length;
+	    int leadSpace = 0;
+	    int endSpace = 0;
+	    if (Tcl_GetIntFromObj(interp, objv[2], &length) != TCL_OK) {
+		return TCL_ERROR;
+	    }
+	    if (objc > 3) {
+		if (Tcl_GetIntFromObj(interp, objv[3], &leadSpace) != TCL_OK) {
+		    return TCL_ERROR;
+		}
+		if (objc > 4) {
+		    if (Tcl_GetIntFromObj(interp, objv[4], &endSpace)
+			!= TCL_OK) {
+			return TCL_ERROR;
+		    }
+		}
+	    }
+	    resultObj = TclListTestObj(length, leadSpace, endSpace);
+	}
+	break;
+
+    case LISTREP_DESCRIBE:
+#define APPEND_FIELD(targetObj_, structPtr_, fld_)                        \
+    do {                                                                  \
+	Tcl_ListObjAppendElement(                                         \
+	    interp, (targetObj_), Tcl_NewStringObj(#fld_, TCL_INDEX_NONE));           \
+	Tcl_ListObjAppendElement(                                         \
+	    interp, (targetObj_), Tcl_NewWideIntObj((structPtr_)->fld_)); \
+    } while (0)
+	if (objc != 3) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "object");
+	    return TCL_ERROR;
+	} else {
+	    Tcl_Obj **objs;
+	    ListSizeT nobjs;
+	    ListRep listRep;
+	    Tcl_Obj *listRepObjs[4];
+
+	    /* Force list representation */
+	    if (Tcl_ListObjGetElements(interp, objv[2], &nobjs, &objs) != TCL_OK) {
+		return TCL_ERROR;
+	    }
+	    ListObjGetRep(objv[2], &listRep);
+	    listRepObjs[0] = Tcl_NewStringObj("store", TCL_INDEX_NONE);
+	    listRepObjs[1] = Tcl_NewListObj(12, NULL);
+	    Tcl_ListObjAppendElement(
+		interp, listRepObjs[1], Tcl_NewStringObj("memoryAddress", TCL_INDEX_NONE));
+	    Tcl_ListObjAppendElement(
+		interp, listRepObjs[1], Tcl_ObjPrintf("%p", listRep.storePtr));
+	    APPEND_FIELD(listRepObjs[1], listRep.storePtr, firstUsed);
+	    APPEND_FIELD(listRepObjs[1], listRep.storePtr, numUsed);
+	    APPEND_FIELD(listRepObjs[1], listRep.storePtr, numAllocated);
+	    APPEND_FIELD(listRepObjs[1], listRep.storePtr, refCount);
+	    APPEND_FIELD(listRepObjs[1], listRep.storePtr, flags);
+	    if (listRep.spanPtr) {
+		listRepObjs[2] = Tcl_NewStringObj("span", TCL_INDEX_NONE);
+		listRepObjs[3] = Tcl_NewListObj(8, NULL);
+		Tcl_ListObjAppendElement(interp,
+					 listRepObjs[3],
+					 Tcl_NewStringObj("memoryAddress", TCL_INDEX_NONE));
+		Tcl_ListObjAppendElement(
+		    interp, listRepObjs[3], Tcl_ObjPrintf("%p", listRep.spanPtr));
+		APPEND_FIELD(listRepObjs[3], listRep.spanPtr, spanStart);
+		APPEND_FIELD(
+		    listRepObjs[3], listRep.spanPtr, spanLength);
+		APPEND_FIELD(listRepObjs[3], listRep.spanPtr, refCount);
+	    }
+	    resultObj = Tcl_NewListObj(listRep.spanPtr ? 4 : 2, listRepObjs);
+	}
+#undef APPEND_FIELD
+	break;
+
+    case LISTREP_CONFIG:
+	if (objc != 2) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "object");
+	    return TCL_ERROR;
+	}
+	resultObj = Tcl_NewListObj(2, NULL);
+	Tcl_ListObjAppendElement(
+	    NULL, resultObj, Tcl_NewStringObj("LIST_SPAN_THRESHOLD", TCL_INDEX_NONE));
+	Tcl_ListObjAppendElement(
+	    NULL, resultObj, Tcl_NewWideIntObj(LIST_SPAN_THRESHOLD));
+	break;
+
+    case LISTREP_VALIDATE:
+	if (objc != 3) {
+	    Tcl_WrongNumArgs(interp, 2, objv, "object");
+	    return TCL_ERROR;
+	}
+	TclListObjValidate(interp, objv[2]); /* Panics if invalid */
+	resultObj = Tcl_NewObj();
+	break;
+    }
+    Tcl_SetObjResult(interp, resultObj);
+    return TCL_OK;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
  * TestlocaleCmd --
  *
  *	This procedure implements the "testlocale" command.  It is used
@@ -3445,7 +3643,7 @@ TestlocaleCmd(
     }
     locale = setlocale(lcTypes[index], locale);
     if (locale) {
-	Tcl_SetStringObj(Tcl_GetObjResult(interp), locale, -1);
+	Tcl_SetStringObj(Tcl_GetObjResult(interp), locale, TCL_INDEX_NONE);
     }
     return TCL_OK;
 }
@@ -3667,7 +3865,7 @@ PrintParse(
 	    break;
 	}
 	Tcl_ListObjAppendElement(NULL, objPtr,
-		Tcl_NewStringObj(typeString, -1));
+		Tcl_NewStringObj(typeString, TCL_INDEX_NONE));
 	Tcl_ListObjAppendElement(NULL, objPtr,
 		Tcl_NewStringObj(tokenPtr->start, tokenPtr->size));
 	Tcl_ListObjAppendElement(NULL, objPtr,
@@ -3676,7 +3874,7 @@ PrintParse(
     Tcl_ListObjAppendElement(NULL, objPtr,
 	    parsePtr->commandStart ?
 	    Tcl_NewStringObj(parsePtr->commandStart + parsePtr->commandSize,
-	    -1) : Tcl_NewObj());
+	    TCL_INDEX_NONE) : Tcl_NewObj());
 }
 
 /*
@@ -3995,7 +4193,7 @@ TestregexpObjCmd(
 	    char resinfo[TCL_INTEGER_SPACE * 2];
 
 	    varName = Tcl_GetString(objv[2]);
-	    TclRegExpRangeUniChar(regExpr, -1, &start, &end);
+	    TclRegExpRangeUniChar(regExpr, TCL_INDEX_NONE, &start, &end);
 	    sprintf(resinfo, "%d %d", start, end-1);
 	    value = Tcl_SetVar2(interp, varName, NULL, resinfo, 0);
 	    if (value == NULL) {
@@ -4035,15 +4233,15 @@ TestregexpObjCmd(
 	Tcl_Obj *newPtr, *varPtr, *valuePtr;
 
 	varPtr = objv[i];
-	ii = ((cflags&REG_EXPECT) && i == objc-1) ? -1 : i;
+	ii = ((cflags&REG_EXPECT) && i == objc-1) ? TCL_INDEX_NONE : i;
 	if (indices) {
 	    Tcl_Obj *objs[2];
 
-	    if (ii == -1) {
+	    if (ii == TCL_INDEX_NONE) {
 		TclRegExpRangeUniChar(regExpr, ii, &start, &end);
 	    } else if (ii > info.nsubs) {
-		start = -1;
-		end = -1;
+		start = TCL_INDEX_NONE;
+		end = TCL_INDEX_NONE;
 	    } else {
 		start = info.matches[ii].start;
 		end = info.matches[ii].end;
@@ -4063,7 +4261,7 @@ TestregexpObjCmd(
 
 	    newPtr = Tcl_NewListObj(2, objs);
 	} else {
-	    if (ii == -1) {
+	    if (ii == TCL_INDEX_NONE) {
 		TclRegExpRangeUniChar(regExpr, ii, &start, &end);
 		newPtr = Tcl_GetRange(objPtr, start, end);
 	    } else if (ii > info.nsubs || info.matches[ii].end <= 0) {
@@ -4111,7 +4309,8 @@ TestregexpXflags(
     int *cflagsPtr,		/* compile flags word */
     int *eflagsPtr)		/* exec flags word */
 {
-    int i, cflags, eflags;
+    int i;
+    int cflags, eflags;
 
     cflags = *cflagsPtr;
     eflags = *eflagsPtr;
@@ -4569,7 +4768,7 @@ TestfeventCmd(
 	    return TCL_ERROR;
 	}
 	if (interp2 != NULL) {
-	    code = Tcl_EvalEx(interp2, argv[2], -1, TCL_EVAL_GLOBAL);
+	    code = Tcl_EvalEx(interp2, argv[2], TCL_INDEX_NONE, TCL_EVAL_GLOBAL);
 	    Tcl_SetObjResult(interp, Tcl_GetObjResult(interp2));
 	    return code;
 	} else {
@@ -4863,15 +5062,15 @@ GetTimesObjCmd(
     ckfree(objv);
 
     /* TclGetString 100000 times */
-    fprintf(stderr, "TclGetStringFromObj of \"12345\" 100000 times\n");
-    objPtr = Tcl_NewStringObj("12345", -1);
+    fprintf(stderr, "Tcl_GetStringFromObj of \"12345\" 100000 times\n");
+    objPtr = Tcl_NewStringObj("12345", TCL_INDEX_NONE);
     Tcl_GetTime(&start);
     for (i = 0;  i < 100000;  i++) {
 	(void) TclGetString(objPtr);
     }
     Tcl_GetTime(&stop);
     timePer = (stop.sec - start.sec)*1000000 + (stop.usec - start.usec);
-    fprintf(stderr, "   %.3f usec per TclGetStringFromObj of \"12345\"\n",
+    fprintf(stderr, "   %.3f usec per Tcl_GetStringFromObj of \"12345\"\n",
 	    timePer/100000);
 
     /* Tcl_GetIntFromObj 100000 times */
@@ -5211,7 +5410,7 @@ Testutf16stringObjCmd(
     }
 
     p = Tcl_GetUnicode(objv[1]);
-    Tcl_SetObjResult(interp, Tcl_NewUnicodeObj(p, -1));
+    Tcl_SetObjResult(interp, Tcl_NewUnicodeObj(p, TCL_INDEX_NONE));
     return TCL_OK;
 }
 
@@ -5349,7 +5548,7 @@ TestsaveresultCmd(
     }
 
     freeCount = 0;
-    objPtr = NULL;		/* Lint. */
+    objPtr = NULL;
     switch ((enum options) index) {
     case RESULT_SMALL:
 	Tcl_AppendResult(interp, "small result", NULL);
@@ -5368,7 +5567,7 @@ TestsaveresultCmd(
 	Tcl_SetResult(interp, (char *)"dynamic result", TestsaveresultFree);
 	break;
     case RESULT_OBJECT:
-	objPtr = Tcl_NewStringObj("object result", -1);
+	objPtr = Tcl_NewStringObj("object result", TCL_INDEX_NONE);
 	Tcl_SetObjResult(interp, objPtr);
 	break;
     }
@@ -5378,7 +5577,7 @@ TestsaveresultCmd(
     if (((enum options) index) == RESULT_OBJECT) {
 	result = Tcl_EvalObjEx(interp, objv[2], 0);
     } else {
-	result = Tcl_EvalEx(interp, Tcl_GetString(objv[2]), -1, 0);
+	result = Tcl_EvalEx(interp, Tcl_GetString(objv[2]), TCL_INDEX_NONE, 0);
     }
 
     if (discard) {
@@ -5630,7 +5829,7 @@ TestChannelCmd(
 
     if ((cmdName[0] == 's') && (strncmp(cmdName, "setchannelerror", len) == 0)) {
 
-	Tcl_Obj *msg = Tcl_NewStringObj(argv[3],-1);
+	Tcl_Obj *msg = Tcl_NewStringObj(argv[3], TCL_INDEX_NONE);
 
 	Tcl_IncrRefCount(msg);
 	Tcl_SetChannelError(chan, msg);
@@ -5643,7 +5842,7 @@ TestChannelCmd(
     }
     if ((cmdName[0] == 's') && (strncmp(cmdName, "setchannelerrorinterp", len) == 0)) {
 
-	Tcl_Obj *msg = Tcl_NewStringObj(argv[3],-1);
+	Tcl_Obj *msg = Tcl_NewStringObj(argv[3], TCL_INDEX_NONE);
 
 	Tcl_IncrRefCount(msg);
 	Tcl_SetChannelErrorInterp(interp, msg);
@@ -5991,7 +6190,7 @@ TestChannelCmd(
 	}
 
 	return TclChannelTransform(interp, chan,
-		Tcl_NewStringObj(argv[4], -1));
+		Tcl_NewStringObj(argv[4], TCL_INDEX_NONE));
     }
 
     if ((cmdName[0] == 'u') && (strncmp(cmdName, "unstack", len) == 0)) {
@@ -6082,7 +6281,7 @@ TestChannelEventCmd(
 	esPtr->chanPtr = chanPtr;
 	esPtr->interp = interp;
 	esPtr->mask = mask;
-	esPtr->scriptPtr = Tcl_NewStringObj(argv[4], -1);
+	esPtr->scriptPtr = Tcl_NewStringObj(argv[4], TCL_INDEX_NONE);
 	Tcl_IncrRefCount(esPtr->scriptPtr);
 
 	Tcl_CreateChannelHandler((Tcl_Channel) chanPtr, mask,
@@ -6149,10 +6348,10 @@ TestChannelEventCmd(
 	     esPtr = esPtr->nextPtr) {
 	    if (esPtr->mask) {
 		Tcl_ListObjAppendElement(interp, resultListPtr, Tcl_NewStringObj(
-		    (esPtr->mask == TCL_READABLE) ? "readable" : "writable", -1));
+		    (esPtr->mask == TCL_READABLE) ? "readable" : "writable", TCL_INDEX_NONE));
 	    } else {
 		Tcl_ListObjAppendElement(interp, resultListPtr,
-			Tcl_NewStringObj("none", -1));
+			Tcl_NewStringObj("none", TCL_INDEX_NONE));
 	    }
 	    Tcl_ListObjAppendElement(interp, resultListPtr, esPtr->scriptPtr);
 	}
@@ -6242,6 +6441,10 @@ TestChannelEventCmd(
  *----------------------------------------------------------------------
  */
 
+#define TCP_ASYNC_TEST_MODE	(1<<8)	/* Async testing activated.  Do not
+					 * automatically continue connection
+					 * process. */
+
 static int
 TestSocketCmd(
     TCL_UNUSED(void *),
@@ -6263,6 +6466,7 @@ TestSocketCmd(
     if ((cmdName[0] == 't') && (strncmp(cmdName, "testflags", len) == 0)) {
         Tcl_Channel hChannel;
         int modePtr;
+        int testMode;
         TcpState *statePtr;
         /* Set test value in the socket driver
          */
@@ -6284,7 +6488,14 @@ TestSocketCmd(
                     NULL);
             return TCL_ERROR;
         }
-        statePtr->testFlags = atoi(argv[3]);
+        if (Tcl_GetBoolean(interp, argv[3], &testMode) != TCL_OK) {
+            return TCL_ERROR;
+        }
+        if (testMode) {
+            statePtr->flags |= TCP_ASYNC_TEST_MODE;
+        } else {
+            statePtr->flags &= ~TCP_ASYNC_TEST_MODE;
+        }
         return TCL_OK;
     }
 
@@ -6364,16 +6575,12 @@ TestWrongNumArgsObjCmd(
     int objc,			/* Number of arguments. */
     Tcl_Obj *const objv[])	/* Argument objects. */
 {
-    int i, length;
+    int i;
+    int length;
     const char *msg;
 
     if (objc < 3) {
-	/*
-	 * Don't use Tcl_WrongNumArgs here, as that is the function
-	 * we want to test!
-	 */
-	Tcl_AppendResult(interp, "insufficient arguments", NULL);
-	return TCL_ERROR;
+	goto insufArgs;
     }
 
     if (Tcl_GetIntFromObj(interp, objv[1], &i) != TCL_OK) {
@@ -6389,6 +6596,7 @@ TestWrongNumArgsObjCmd(
 	/*
 	 * Asked for more arguments than were given.
 	 */
+    insufArgs:
 	Tcl_AppendResult(interp, "insufficient arguments", NULL);
 	return TCL_ERROR;
     }
@@ -6499,7 +6707,7 @@ TestFilesystemObjCmd(
 	res = Tcl_FSUnregister(&testReportingFilesystem);
 	msg = (res == TCL_OK) ? "unregistered" : "failed";
     }
-    Tcl_SetObjResult(interp, Tcl_NewStringObj(msg , -1));
+    Tcl_SetObjResult(interp, Tcl_NewStringObj(msg , TCL_INDEX_NONE));
     return res;
 }
 
@@ -6581,7 +6789,7 @@ TestReport(
 	Tcl_DString ds;
 
 	Tcl_DStringInit(&ds);
-	Tcl_DStringAppend(&ds, "lappend filesystemReport ", -1);
+	Tcl_DStringAppend(&ds, "lappend filesystemReport ", TCL_INDEX_NONE);
 	Tcl_DStringStartSublist(&ds);
 	Tcl_DStringAppendElement(&ds, cmd);
 	if (path != NULL) {
@@ -6594,7 +6802,7 @@ TestReport(
 	savedResult = Tcl_GetObjResult(interp);
 	Tcl_IncrRefCount(savedResult);
 	Tcl_SetObjResult(interp, Tcl_NewObj());
-	Tcl_EvalEx(interp, Tcl_DStringValue(&ds), -1, 0);
+	Tcl_EvalEx(interp, Tcl_DStringValue(&ds), TCL_INDEX_NONE, 0);
 	Tcl_DStringFree(&ds);
 	Tcl_ResetResult(interp);
 	Tcl_SetObjResult(interp, savedResult);
@@ -6870,7 +7078,7 @@ TestSimpleFilesystemObjCmd(
 	res = Tcl_FSUnregister(&simpleFilesystem);
 	msg = (res == TCL_OK) ? "unregistered" : "failed";
     }
-    Tcl_SetObjResult(interp, Tcl_NewStringObj(msg , -1));
+    Tcl_SetObjResult(interp, Tcl_NewStringObj(msg , TCL_INDEX_NONE));
     return res;
 }
 
@@ -6897,7 +7105,7 @@ SimpleRedirect(
 	Tcl_IncrRefCount(pathPtr);
 	return pathPtr;
     }
-    origPtr = Tcl_NewStringObj(str+10,-1);
+    origPtr = Tcl_NewStringObj(str+10, TCL_INDEX_NONE);
     Tcl_IncrRefCount(origPtr);
     return origPtr;
 }
@@ -6997,7 +7205,7 @@ SimpleListVolumes(void)
     /* Add one new volume */
     Tcl_Obj *retVal;
 
-    retVal = Tcl_NewStringObj("simplefs:/", -1);
+    retVal = Tcl_NewStringObj("simplefs:/", TCL_INDEX_NONE);
     Tcl_IncrRefCount(retVal);
     return retVal;
 }
@@ -7117,7 +7325,7 @@ TestNumUtfCharsCmd(
     Tcl_Obj *const objv[])
 {
     if (objc > 1) {
-	int numBytes, len, limit = -1;
+	int numBytes, len, limit = TCL_INDEX_NONE;
 	const char *bytes = Tcl_GetStringFromObj(objv[1], &numBytes);
 
 	if (objc > 2) {
@@ -7151,7 +7359,7 @@ TestFindFirstCmd(
 	if (objc > 2) {
 	    (void) Tcl_GetIntFromObj(interp, objv[2], &len);
 	}
-	Tcl_SetObjResult(interp, Tcl_NewStringObj(Tcl_UtfFindFirst(Tcl_GetString(objv[1]), len), -1));
+	Tcl_SetObjResult(interp, Tcl_NewStringObj(Tcl_UtfFindFirst(Tcl_GetString(objv[1]), len), TCL_INDEX_NONE));
     }
     return TCL_OK;
 }
@@ -7173,7 +7381,7 @@ TestFindLastCmd(
 	if (objc > 2) {
 	    (void) Tcl_GetIntFromObj(interp, objv[2], &len);
 	}
-	Tcl_SetObjResult(interp, Tcl_NewStringObj(Tcl_UtfFindLast(Tcl_GetString(objv[1]), len), -1));
+	Tcl_SetObjResult(interp, Tcl_NewStringObj(Tcl_UtfFindLast(Tcl_GetString(objv[1]), len), TCL_INDEX_NONE));
     }
     return TCL_OK;
 }
@@ -7250,7 +7458,7 @@ TestcpuidCmd(
     status = TclWinCPUID(index, regs);
     if (status != TCL_OK) {
 	Tcl_SetObjResult(interp,
-		Tcl_NewStringObj("operation not available", -1));
+		Tcl_NewStringObj("operation not available", TCL_INDEX_NONE));
 	return status;
     }
     for (i=0 ; i<4 ; ++i) {
@@ -7296,7 +7504,7 @@ TestHashSystemHashCmd(
 	hPtr = Tcl_CreateHashEntry(&hash, INT2PTR(i), &isNew);
 	if (!isNew) {
 	    Tcl_SetObjResult(interp, Tcl_NewWideIntObj(i));
-	    Tcl_AppendToObj(Tcl_GetObjResult(interp)," creation problem",-1);
+	    Tcl_AppendToObj(Tcl_GetObjResult(interp)," creation problem", TCL_INDEX_NONE);
 	    Tcl_DeleteHashTable(&hash);
 	    return TCL_ERROR;
 	}
@@ -7313,13 +7521,13 @@ TestHashSystemHashCmd(
 	hPtr = Tcl_FindHashEntry(&hash, (char *) INT2PTR(i));
 	if (hPtr == NULL) {
 	    Tcl_SetObjResult(interp, Tcl_NewWideIntObj(i));
-	    Tcl_AppendToObj(Tcl_GetObjResult(interp)," lookup problem",-1);
+	    Tcl_AppendToObj(Tcl_GetObjResult(interp)," lookup problem", TCL_INDEX_NONE);
 	    Tcl_DeleteHashTable(&hash);
 	    return TCL_ERROR;
 	}
 	if (PTR2INT(Tcl_GetHashValue(hPtr)) != i+42) {
 	    Tcl_SetObjResult(interp, Tcl_NewWideIntObj(i));
-	    Tcl_AppendToObj(Tcl_GetObjResult(interp)," value problem",-1);
+	    Tcl_AppendToObj(Tcl_GetObjResult(interp)," value problem", TCL_INDEX_NONE);
 	    Tcl_DeleteHashTable(&hash);
 	    return TCL_ERROR;
 	}
@@ -7402,9 +7610,9 @@ NREUnwind_callback(
                 &none, NULL);
     } else {
         Tcl_Obj *idata[3];
-        idata[0] = Tcl_NewWideIntObj((int) ((char *) data[1] - (char *) data[0]));
-        idata[1] = Tcl_NewWideIntObj((int) ((char *) data[2] - (char *) data[0]));
-        idata[2] = Tcl_NewWideIntObj((int) ((char *) &none   - (char *) data[0]));
+        idata[0] = Tcl_NewWideIntObj(((char *) data[1] - (char *) data[0]));
+        idata[1] = Tcl_NewWideIntObj(((char *) data[2] - (char *) data[0]));
+        idata[2] = Tcl_NewWideIntObj(((char *) &none   - (char *) data[0]));
         Tcl_SetObjResult(interp, Tcl_NewListObj(3, idata));
     }
     return TCL_OK;
@@ -7502,15 +7710,15 @@ TestconcatobjCmd(
      */
 
     Tcl_SetObjResult(interp,
-	    Tcl_NewStringObj("Tcl_ConcatObj is unsafe:", -1));
+	    Tcl_NewStringObj("Tcl_ConcatObj is unsafe:", TCL_INDEX_NONE));
 
     emptyPtr = Tcl_NewObj();
 
-    list1Ptr = Tcl_NewStringObj("foo bar sum", -1);
+    list1Ptr = Tcl_NewStringObj("foo bar sum", TCL_INDEX_NONE);
     Tcl_ListObjLength(NULL, list1Ptr, &len);
     Tcl_InvalidateStringRep(list1Ptr);
 
-    list2Ptr = Tcl_NewStringObj("eeny meeny", -1);
+    list2Ptr = Tcl_NewStringObj("eeny meeny", TCL_INDEX_NONE);
     Tcl_ListObjLength(NULL, list2Ptr, &len);
     Tcl_InvalidateStringRep(list2Ptr);
 
@@ -8073,7 +8281,7 @@ InterpCompiledVarResolver(
  	resVarInfo->vInfo.fetchProc = MyCompiledVarFetch;
  	resVarInfo->vInfo.deleteProc = MyCompiledVarFree;
  	resVarInfo->var = NULL;
- 	resVarInfo->nameObj = Tcl_NewStringObj(name, -1);
+ 	resVarInfo->nameObj = Tcl_NewStringObj(name, TCL_INDEX_NONE);
  	Tcl_IncrRefCount(resVarInfo->nameObj);
  	*rPtr = &resVarInfo->vInfo;
  	return TCL_OK;
@@ -8157,12 +8365,12 @@ int TestApplyLambdaObjCmd (
 
     /* Create a lambda {{} {set a 42}} */
     lambdaObjs[0] = Tcl_NewObj(); /* No parameters */
-    lambdaObjs[1] = Tcl_NewStringObj("set a 42", -1); /* Body */
+    lambdaObjs[1] = Tcl_NewStringObj("set a 42", TCL_INDEX_NONE); /* Body */
     lambdaObj = Tcl_NewListObj(2, lambdaObjs);
     Tcl_IncrRefCount(lambdaObj);
 
     /* Create the command "apply {{} {set a 42}" */
-    evalObjs[0] = Tcl_NewStringObj("apply", -1);
+    evalObjs[0] = Tcl_NewStringObj("apply", TCL_INDEX_NONE);
     Tcl_IncrRefCount(evalObjs[0]);
     /*
      * NOTE: IMPORTANT TO EXHIBIT THE BUG. We duplicate the lambda because
diff --git a/generic/tclTrace.c b/generic/tclTrace.c
index c8f10e3..0c243a6 100644
--- a/generic/tclTrace.c
+++ b/generic/tclTrace.c
@@ -1759,7 +1759,7 @@ TraceExecutionProc(
     const char *command,
     TCL_UNUSED(Tcl_Command),
     int objc,
-    struct Tcl_Obj *const objv[])
+    Tcl_Obj *const objv[])
 {
     int call = 0;
     Interp *iPtr = (Interp *) interp;
@@ -2121,6 +2121,54 @@ TraceVarProc(
  *----------------------------------------------------------------------
  */
 
+typedef struct {
+    Tcl_CmdObjTraceProc2 *proc;
+    Tcl_CmdObjTraceDeleteProc *delProc;
+    void *clientData;
+} TraceWrapperInfo;
+
+static int traceWrapperProc(
+    void *clientData,
+    Tcl_Interp *interp,
+	int level,
+    const char *command,
+    Tcl_Command commandInfo,
+    int objc,
+    Tcl_Obj *const objv[])
+{
+    TraceWrapperInfo *info = (TraceWrapperInfo *)clientData;
+    return info->proc(info->clientData, interp, level, command, commandInfo, objc, objv);
+}
+
+static void traceWrapperDelProc(void *clientData)
+{
+    TraceWrapperInfo *info = (TraceWrapperInfo *)clientData;
+    clientData = info->clientData;
+    if (info->delProc) {
+	info->delProc(clientData);
+    }
+    ckfree(info);
+}
+
+Tcl_Trace
+Tcl_CreateObjTrace2(
+    Tcl_Interp *interp,		/* Tcl interpreter */
+    int level,			/* Maximum nesting level */
+    int flags,			/* Flags, see above */
+    Tcl_CmdObjTraceProc2 *proc,	/* Trace callback */
+    void *clientData,	/* Client data for the callback */
+    Tcl_CmdObjTraceDeleteProc *delProc)
+				/* Function to call when trace is deleted */
+{
+    TraceWrapperInfo *info = (TraceWrapperInfo *)ckalloc(sizeof(TraceWrapperInfo));
+    info->proc = proc;
+    info->delProc = delProc;
+    info->clientData = clientData;
+    return Tcl_CreateObjTrace(interp, level, flags,
+	    (proc ? traceWrapperProc : NULL),
+	    info, traceWrapperDelProc);
+}
+
 Tcl_Trace
 Tcl_CreateObjTrace(
     Tcl_Interp *interp,		/* Tcl interpreter */
diff --git a/library/http/http.tcl b/library/http/http.tcl
index 48e1b4b..38e07cc 100644
--- a/library/http/http.tcl
+++ b/library/http/http.tcl
@@ -27,6 +27,7 @@ namespace eval http {
 	    -proxyport {}
 	    -proxyfilter http::ProxyRequired
 	    -repost 0
+	    -threadlevel 0
 	    -urlencoding utf-8
 	    -zip 1
 	}
@@ -70,8 +71,10 @@ namespace eval http {
 	variable socketWrState
 	variable socketRdQueue
 	variable socketWrQueue
+	variable socketPhQueue
 	variable socketClosing
 	variable socketPlayCmd
+	variable socketCoEvent
 	if {[info exists socketMapping]} {
 	    # Close open sockets on re-init.  Do not permit retries.
 	    foreach {url sock} [array get socketMapping] {
@@ -92,21 +95,26 @@ namespace eval http {
 	array unset socketWrState
 	array unset socketRdQueue
 	array unset socketWrQueue
+	array unset socketPhQueue
 	array unset socketClosing
 	array unset socketPlayCmd
+	array unset socketCoEvent
 	array set socketMapping {}
 	array set socketRdState {}
 	array set socketWrState {}
 	array set socketRdQueue {}
 	array set socketWrQueue {}
+	array set socketPhQueue {}
 	array set socketClosing {}
 	array set socketPlayCmd {}
+	array set socketCoEvent {}
+	return
     }
     init
 
     variable urlTypes
     if {![info exists urlTypes]} {
-	set urlTypes(http) [list 80 ::socket]
+	set urlTypes(http) [list 80 ::http::socket]
     }
 
     variable encodings [string tolower [encoding names]]
@@ -140,6 +148,9 @@ namespace eval http {
 	)?
     }
 
+    variable TmpSockCounter 0
+    variable ThreadCounter  0
+
     namespace export geturl config reset wait formatQuery quoteString
     namespace export register unregister registerError
     # - Useful, but not exported: data, size, status, code, cleanup, error,
@@ -223,13 +234,20 @@ proc http::config {args} {
 	    return -code error "Unknown option $flag, must be: $usage"
 	}
 	return $http($flag)
+    } elseif {[llength $args] % 2} {
+	return -code error "If more than one argument is supplied, the\
+		number of arguments must be even"
     } else {
 	foreach {flag value} $args {
 	    if {![regexp -- $pat $flag]} {
 		return -code error "Unknown option $flag, must be: $usage"
 	    }
+	    if {($flag eq {-threadlevel}) && ($value ni {0 1 2})} {
+		return -code error {Option -threadlevel must be 0, 1 or 2}
+	    }
 	    set http($flag) $value
 	}
+	return
     }
 }
 
@@ -254,8 +272,10 @@ proc http::Finish {token {errormsg ""} {skipCB 0}} {
     variable socketWrState
     variable socketRdQueue
     variable socketWrQueue
+    variable socketPhQueue
     variable socketClosing
     variable socketPlayCmd
+    variable socketCoEvent
 
     variable $token
     upvar 0 $token state
@@ -265,16 +285,29 @@ proc http::Finish {token {errormsg ""} {skipCB 0}} {
 	set state(error) [list $errormsg $errorInfo $errorCode]
 	set state(status) "error"
     }
-    if {[info commands ${token}EventCoroutine] ne {}} {
-	rename ${token}EventCoroutine {}
+    if {[info commands ${token}--EventCoroutine] ne {}} {
+	rename ${token}--EventCoroutine {}
+    }
+    if {[info commands ${token}--SocketCoroutine] ne {}} {
+	rename ${token}--SocketCoroutine {}
+    }
+    if {[info exists state(socketcoro)]} {
+        Log $token Cancel socket after-idle event (Finish)
+        after cancel $state(socketcoro)
+        unset state(socketcoro)
     }
 
     # Is this an upgrade request/response?
     set upgradeResponse \
-	[expr {    [info exists state(upgradeRequest)] && $state(upgradeRequest)
-		&& [info exists state(http)] && [ncode $token] eq {101}
-		&& [info exists state(connection)] && "upgrade" in $state(connection)
-		&& [info exists state(upgrade)] && "" ne $state(upgrade)}]
+	[expr {    [info exists state(upgradeRequest)]
+		&& $state(upgradeRequest)
+		&& [info exists state(http)]
+		&& ([ncode $token] eq {101})
+		&& [info exists state(connection)]
+		&& ("upgrade" in $state(connection))
+		&& [info exists state(upgrade)]
+		&& ("" ne $state(upgrade))
+	}]
 
     if {  ($state(status) eq "timeout")
        || ($state(status) eq "error")
@@ -282,8 +315,22 @@ proc http::Finish {token {errormsg ""} {skipCB 0}} {
     } {
 	set closeQueue 1
 	set connId $state(socketinfo)
-	set sock $state(sock)
-	CloseSocket $state(sock) $token
+	if {[info exists state(sock)]} {
+	    set sock $state(sock)
+	    CloseSocket $state(sock) $token
+	} else {
+            # When opening the socket and calling http::reset
+            # immediately, the socket may not yet exist.
+            # Test http-4.11 may come here.
+	}
+	if {$state(tid) ne {}} {
+            # When opening the socket in a thread, and calling http::reset
+            # immediately, the thread may still exist.
+            # Test http-4.11 may come here.
+	    thread::release $state(tid)
+	    set state(tid) {}
+	} else {
+	}
     } elseif {$upgradeResponse} {
 	# Special handling for an upgrade request/response.
 	# - geturl ensures that this is not a "persistent" socket used for
@@ -300,8 +347,14 @@ proc http::Finish {token {errormsg ""} {skipCB 0}} {
     } {
 	set closeQueue 1
 	set connId $state(socketinfo)
-	set sock $state(sock)
-	CloseSocket $state(sock) $token
+	if {[info exists state(sock)]} {
+	    set sock $state(sock)
+	    CloseSocket $state(sock) $token
+	} else {
+            # When opening the socket and calling http::reset
+            # immediately, the socket may not yet exist.
+            # Test http-4.11 may come here.
+	}
     } elseif {
 	  ([info exists state(-keepalive)] && $state(-keepalive))
        && ([info exists state(connection)] && ("close" ni $state(connection)))
@@ -326,7 +379,9 @@ proc http::Finish {token {errormsg ""} {skipCB 0}} {
 	 && ($socketMapping($connId) eq $sock)
     } {
 	http::CloseQueuedQueries $connId $token
+	# This calls Unset.  Other cases do not need the call.
     }
+    return
 }
 
 # http::KeepSocket -
@@ -348,8 +403,10 @@ proc http::KeepSocket {token} {
     variable socketWrState
     variable socketRdQueue
     variable socketWrQueue
+    variable socketPhQueue
     variable socketClosing
     variable socketPlayCmd
+    variable socketCoEvent
 
     variable $token
     upvar 0 $token state
@@ -384,9 +441,6 @@ proc http::KeepSocket {token} {
 	    # queued, arrange to read it.
 	    set token3 [lindex $socketRdQueue($connId) 0]
 	    set socketRdQueue($connId) [lrange $socketRdQueue($connId) 1 end]
-	    variable $token3
-	    upvar 0 $token3 state3
-	    set tk2 [namespace tail $token3]
 
 	    #Log pipelined, GRANT read access to $token3 in KeepSocket
 	    set socketRdState($connId) $token3
@@ -425,8 +479,7 @@ proc http::KeepSocket {token} {
 	    #   first item in the write queue, a non-pipelined request that is
 	    #   waiting for the read queue to empty.  That has now happened: so
 	    #   give that request read and write access.
-	    variable $token3
-	    set conn [set ${token3}(tmpConnArgs)]
+	    set conn [set ${token3}(connArgs)]
 	    #Log nonpipeline, GRANT r/w access to $token3 in KeepSocket
 	    set socketRdState($connId) $token3
 	    set socketWrState($connId) $token3
@@ -470,8 +523,7 @@ proc http::KeepSocket {token} {
 	    # Code:
 	    # - The code is the same as the code below for the nonpipelined
 	    #   case with a queued request.
-	    variable $token3
-	    set conn [set ${token3}(tmpConnArgs)]
+	    set conn [set ${token3}(connArgs)]
 	    #Log nonpipeline, GRANT r/w access to $token3 in KeepSocket
 	    set socketRdState($connId) $token3
 	    set socketWrState($connId) $token3
@@ -492,8 +544,7 @@ proc http::KeepSocket {token} {
 	    # If the next request is pipelined, it receives premature read
 	    # access to the socket. This is not a problem.
 	    set token3 [lindex $socketWrQueue($connId) 0]
-	    variable $token3
-	    set conn [set ${token3}(tmpConnArgs)]
+	    set conn [set ${token3}(connArgs)]
 	    #Log nonpipeline, GRANT r/w access to $token3 in KeepSocket
 	    set socketRdState($connId) $token3
 	    set socketWrState($connId) $token3
@@ -512,6 +563,7 @@ proc http::KeepSocket {token} {
 	# There is no socketMapping($state(socketinfo)), so it does not matter
 	# that CloseQueuedQueries is not called.
     }
+    return
 }
 
 # http::CheckEof -
@@ -537,6 +589,7 @@ proc http::CheckEof {sock} {
 	# will then be error-handled.
 	CloseSocket $sock
     }
+    return
 }
 
 # http::CloseSocket -
@@ -552,8 +605,10 @@ proc http::CloseSocket {s {token {}}} {
     variable socketWrState
     variable socketRdQueue
     variable socketWrQueue
+    variable socketPhQueue
     variable socketClosing
     variable socketPlayCmd
+    variable socketCoEvent
 
     set tk [namespace tail $token]
 
@@ -580,18 +635,22 @@ proc http::CloseSocket {s {token {}}} {
 	Log "Closing connection $connId (sock $socketMapping($connId))"
 	if {[catch {close $socketMapping($connId)} err]} {
 	    Log "Error closing connection: $err"
+	} else {
 	}
 	if {$token eq {}} {
 	    # Cases with a non-empty token are handled by Finish, so the tokens
 	    # are finished in connection order.
 	    http::CloseQueuedQueries $connId
+	} else {
 	}
     } else {
 	Log "Closing socket $s (no connection info)"
 	if {[catch {close $s} err]} {
 	    Log "Error closing socket: $err"
+	} else {
 	}
     }
+    return
 }
 
 # http::CloseQueuedQueries
@@ -608,9 +667,12 @@ proc http::CloseQueuedQueries {connId {token {}}} {
     variable socketWrState
     variable socketRdQueue
     variable socketWrQueue
+    variable socketPhQueue
     variable socketClosing
     variable socketPlayCmd
+    variable socketCoEvent
 
+    ##Log CloseQueuedQueries $connId
     if {![info exists socketMapping($connId)]} {
 	# Command has already been called.
 	# Don't come here again - especially recursively.
@@ -634,6 +696,7 @@ proc http::CloseQueuedQueries {connId {token {}}} {
 	# - Also clear the queues to prevent calls to Finish that would set the
 	#   state for the requests that will be retried to "finished with error
 	#   status".
+	# - At this stage socketPhQueue is empty.
 	set unfinished $socketPlayCmd($connId)
 	set socketRdQueue($connId) {}
 	set socketWrQueue($connId) {}
@@ -645,9 +708,11 @@ proc http::CloseQueuedQueries {connId {token {}}} {
 
     if {$unfinished ne {}} {
 	Log ^R$tk Any unfinished transactions (excluding $token) failed \
-		- token $token
+		- token $token - unfinished $unfinished
 	{*}$unfinished
+	# Calls ReplayIfClose.
     }
+    return
 }
 
 # http::Unset
@@ -663,8 +728,10 @@ proc http::Unset {connId} {
     variable socketWrState
     variable socketRdQueue
     variable socketWrQueue
+    variable socketPhQueue
     variable socketClosing
     variable socketPlayCmd
+    variable socketCoEvent
 
     unset socketMapping($connId)
     unset socketRdState($connId)
@@ -673,6 +740,7 @@ proc http::Unset {connId} {
     unset -nocomplain socketWrQueue($connId)
     unset -nocomplain socketClosing($connId)
     unset -nocomplain socketPlayCmd($connId)
+    return
 }
 
 # http::reset --
@@ -698,6 +766,7 @@ proc http::reset {token {why reset}} {
 	unset state
 	eval ::error $errorlist
     }
+    return
 }
 
 # http::geturl --
@@ -713,15 +782,100 @@ proc http::reset {token {why reset}} {
 #	array that the caller should unset to garbage collect the state.
 
 proc http::geturl {url args} {
+    variable urlTypes
+
+    # The value is set in the namespace header of this file.  If the file has
+    # not been modified the value is "::http::socket".
+    set socketCmd [lindex $urlTypes(http) 1]
+
+    # - If ::tls::socketCmd has its default value "::socket", change it to the
+    #   new value $socketCmd.
+    # - If the old value is different, then it has been modified either by the
+    #   script or by the Tcl installation, and replaced by a new command.  The
+    #   script or installation that modified ::tls::socketCmd is also
+    #   responsible for integrating ::http::socket into its own "new" command,
+    #   if it wishes to do so.
+    
+    if {[info exists ::tls::socketCmd] && ($::tls::socketCmd eq {::socket})} {
+        set ::tls::socketCmd $socketCmd
+    }
+
+    set token [CreateToken $url {*}$args]
+    variable $token
+    upvar 0 $token state
+
+    AsyncTransaction $token
+
+    # --------------------------------------------------------------------------
+    # Synchronous Call to http::geturl
+    # --------------------------------------------------------------------------
+    # - If the call to http::geturl is asynchronous, it is now complete (apart
+    #   from delivering the return value).
+    # - If the call to http::geturl is synchronous, the command must now wait
+    #   for the HTTP transaction to be completed.  The call to http::wait uses
+    #   vwait, which may be inappropriate if the caller makes other HTTP
+    #   requests in the background.
+    # --------------------------------------------------------------------------
+
+    if {![info exists state(-command)]} {
+	# geturl does EVERYTHING asynchronously, so if the user
+	# calls it synchronously, we just do a wait here.
+	http::wait $token
+
+	if {![info exists state]} {
+	    # If we timed out then Finish has been called and the users
+	    # command callback may have cleaned up the token. If so we end up
+	    # here with nothing left to do.
+	    return $token
+	} elseif {$state(status) eq "error"} {
+	    # Something went wrong while trying to establish the connection.
+	    # Clean up after events and such, but DON'T call the command
+	    # callback (if available) because we're going to throw an
+	    # exception from here instead.
+	    set err [lindex $state(error) 0]
+	    cleanup $token
+	    return -code error $err
+	}
+    }
+
+    return $token
+}
+
+# ------------------------------------------------------------------------------
+#  Proc http::CreateToken
+# ------------------------------------------------------------------------------
+# Command to convert arguments into an initialised request token.
+# The return value is the variable name of the token.
+#
+# Other effects:
+# - Sets ::http::http(usingThread) if not already done
+# - Sets ::http::http(uid) if not already done
+# - Increments ::http::http(uid)
+# - May increment ::http::TmpSockCounter
+# - Alters ::http::socketPlayCmd, ::http::socketWrQueue if a -keepalive 1
+#   request is appended to the queue of a persistent socket that is already
+#   scheduled to close.
+#   This also sets state(alreadyQueued) to 1.
+# - Alters ::http::socketPhQueue if a -keepalive 1 request is appended to the
+#   queue of a persistent socket that has not yet been created (and is therefore
+#   represented by a placeholder).
+#   This also sets state(ReusingPlaceholder) to 1.
+# ------------------------------------------------------------------------------
+
+proc http::CreateToken {url args} {
     variable http
     variable urlTypes
     variable defaultCharset
     variable defaultKeepalive
     variable strict
+    variable TmpSockCounter
 
     # Initialize the state variable, an array. We'll return the name of this
     # array as the token for the transaction.
 
+    if {![info exists http(usingThread)]} {
+	set http(usingThread) 0
+    }
     if {![info exists http(uid)]} {
 	set http(uid) 0
     }
@@ -759,6 +913,7 @@ proc http::geturl {url args} {
 	status		""
 	http		""
 	connection	keep-alive
+	tid             {}
     }
     set state(-keepalive) $defaultKeepalive
     set state(-strict) $strict
@@ -793,8 +948,8 @@ proc http::geturl {url args} {
 	    }
 	    if {($flag eq "-headers") && ([llength $value] % 2 != 0)} {
 		unset $token
-		return -code error \
-		    "Bad value for $flag ($value), number of list elements must be even"
+		return -code error "Bad value for $flag ($value), number\
+			of list elements must be even"
 	    }
 	    set state($flag) $value
 	} else {
@@ -958,6 +1113,9 @@ proc http::geturl {url args} {
     if {![catch {$http(-proxyfilter) $host} proxy]} {
 	set phost [lindex $proxy 0]
 	set pport [lindex $proxy 1]
+    } else {
+	set phost {}
+	set pport {}
     }
 
     # OK, now reassemble into a full URL
@@ -971,20 +1129,9 @@ proc http::geturl {url args} {
 	append url : $port
     }
     append url $srvurl
-    # Don't append the fragment!
+    # Don't append the fragment! RFC 7230 Sec 5.1
     set state(url) $url
 
-    set sockopts [list -async]
-
-    # If we are using the proxy, we must pass in the full URL that includes
-    # the server name.
-
-    if {[info exists phost] && ($phost ne "")} {
-	set srvurl $url
-	set targetAddr [list $phost $pport]
-    } else {
-	set targetAddr [list $host $port]
-    }
     # Proxy connections aren't shared among different hosts.
     set state(socketinfo) $host:$port
 
@@ -1038,6 +1185,25 @@ proc http::geturl {url args} {
 	set state(-keepalive) 0
     }
 
+    # If we are using the proxy, we must pass in the full URL that includes
+    # the server name.
+    if {$phost ne ""} {
+	set srvurl $url
+	set targetAddr [list $phost $pport]
+    } else {
+	set targetAddr [list $host $port]
+    }
+
+    set sockopts [list -async]
+
+    # Pass -myaddr directly to the socket command
+    if {[info exists state(-myaddr)]} {
+	lappend sockopts -myaddr $state(-myaddr)
+    }
+
+    set state(connArgs) [list $proto $phost $srvurl]
+    set state(openCmd) [list {*}$defcmd {*}$sockopts {*}$targetAddr]
+
     # See if we are supposed to use a previously opened channel.
     # - In principle, ANY call to http::geturl could use a previously opened
     #   channel if it is available - the "Connection: keep-alive" header is a
@@ -1047,15 +1213,18 @@ proc http::geturl {url args} {
     #   $state(socketinfo). This property simplifies the mapping of open
     #   channels.
     set reusing 0
-    set alreadyQueued 0
+    set state(alreadyQueued) 0
+    set state(ReusingPlaceholder) 0
     if {$state(-keepalive)} {
 	variable socketMapping
 	variable socketRdState
 	variable socketWrState
 	variable socketRdQueue
 	variable socketWrQueue
+	variable socketPhQueue
 	variable socketClosing
 	variable socketPlayCmd
+	variable socketCoEvent
 
 	if {[info exists socketMapping($state(socketinfo))]} {
 	    # - If the connection is idle, it has a "fileevent readable" binding
@@ -1078,14 +1247,20 @@ proc http::geturl {url args} {
 		# causes a call to Finish.
 		set reusing 1
 		set sock $socketMapping($state(socketinfo))
-		Log "reusing socket $sock for $state(socketinfo) - token $token"
+		Log "reusing closing socket $sock for $state(socketinfo) - token $token"
 
-		set alreadyQueued 1
+		set state(alreadyQueued) 1
 		lassign $socketPlayCmd($state(socketinfo)) com0 com1 com2 com3
 		lappend com3 $token
 		set socketPlayCmd($state(socketinfo)) [list $com0 $com1 $com2 $com3]
 		lappend socketWrQueue($state(socketinfo)) $token
-	    } elseif {[catch {fconfigure $socketMapping($state(socketinfo))}]} {
+		##Log socketPlayCmd($state(socketinfo)) is $socketPlayCmd($state(socketinfo))
+		##Log socketWrQueue($state(socketinfo)) is $socketWrQueue($state(socketinfo))
+	    } elseif {
+		   [catch {fconfigure $socketMapping($state(socketinfo))}]
+		&& (![SockIsPlaceHolder $socketMapping($state(socketinfo))])
+	    } {
+		###Log "Socket $socketMapping($state(socketinfo)) for $state(socketinfo)"
 		# FIXME Is it still possible for this code to be executed? If
 		#       so, this could be another place to call TestForReplay,
 		#       rather than discarding the queued transactions.
@@ -1099,43 +1274,113 @@ proc http::geturl {url args} {
 		Unset $state(socketinfo)
 	    } else {
 		# Use the persistent socket.
-		# The socket may not be ready to write: an earlier request might
-		# still be still writing (in the pipelined case) or
-		# writing/reading (in the nonpipeline case). This possibility
-		# is handled by socketWrQueue later in this command.
+		# - The socket may not be ready to write: an earlier request might
+		#   still be still writing (in the pipelined case) or
+		#   writing/reading (in the nonpipeline case). This possibility
+		#   is handled by socketWrQueue later in this command.
+		# - The socket may not yet exist, and be defined with a placeholder.
 		set reusing 1
 		set sock $socketMapping($state(socketinfo))
-		Log "reusing socket $sock for $state(socketinfo) - token $token"
-
+		if {[SockIsPlaceHolder $sock]} {
+		    set state(ReusingPlaceholder) 1
+		    lappend socketPhQueue($sock) $token
+		} else {
+		}
+		Log "reusing open socket $sock for $state(socketinfo) - token $token"
 	    }
 	    # Do not automatically close the connection socket.
 	    set state(connection) keep-alive
 	}
     }
 
-    if {$reusing} {
-	# Define state(tmpState) and state(tmpOpenCmd) for use
-	# by http::ReplayIfDead if the persistent connection has died.
-	set state(tmpState) [array get state]
+    set state(reusing) $reusing
+    unset reusing
 
-	# Pass -myaddr directly to the socket command
-	if {[info exists state(-myaddr)]} {
-	    lappend sockopts -myaddr $state(-myaddr)
-	}
+    if {![info exists sock]} {
+        # N.B. At this point ([info exists sock] == $state(reusing)).
+        # This will no longer be true after we set a value of sock here.
+	# Give the socket a placeholder name.
+	set sock HTTP_PLACEHOLDER_[incr TmpSockCounter]
+    }
+    set state(sock) $sock
 
-	set state(tmpOpenCmd) [list {*}$defcmd {*}$sockopts {*}$targetAddr]
+    if {$state(reusing)} {
+	# Define these for use (only) by http::ReplayIfDead if the persistent
+	# connection has died.
+	set state(tmpConnArgs) $state(connArgs)
+	set state(tmpState) [array get state]
+	set state(tmpOpenCmd) $state(openCmd)
     }
+    return $token
+}
 
-    set state(reusing) $reusing
-    # Excluding ReplayIfDead and the decision whether to call it, there are four
-    # places outside http::geturl where state(reusing) is used:
-    # - Connected   - if reusing and not pipelined, start the state(-timeout)
-    #                 timeout (when writing).
-    # - DoneRequest - if reusing and pipelined, send the next pipelined write
-    # - Event       - if reusing and pipelined, start the state(-timeout)
-    #                 timeout (when reading).
-    # - Event       - if (not reusing) and pipelined, send the next pipelined
-    #                 write
+
+# ------------------------------------------------------------------------------
+#  Proc ::http::SockIsPlaceHolder
+# ------------------------------------------------------------------------------
+# Command to return 0 if the argument is a genuine socket handle, or 1 if is a
+# placeholder value generated by geturl or ReplayCore before the real socket is
+# created.
+#
+# Arguments:
+# sock        - either a valid socket handle or a placeholder value
+#
+# Return Value: 0 or 1
+# ------------------------------------------------------------------------------
+
+proc http::SockIsPlaceHolder {sock} {
+    expr {[string range $sock 0 16] eq {HTTP_PLACEHOLDER_}}
+}
+
+
+# ------------------------------------------------------------------------------
+# state(reusing)
+# ------------------------------------------------------------------------------
+# - state(reusing) is set by geturl, ReplayCore
+# - state(reusing) is used by geturl, AsyncTransaction, OpenSocket,
+#   ConfigureNewSocket, and ScheduleRequest when creating and configuring the
+#   connection.
+# - state(reusing) is used by Connect, Connected, Event x 2 when deciding
+#   whether to call TestForReplay.
+# - Other places where state(reusing) is used:
+#   - Connected   - if reusing and not pipelined, start the state(-timeout)
+#                   timeout (when writing).
+#   - DoneRequest - if reusing and pipelined, send the next pipelined write
+#   - Event       - if reusing and pipelined, start the state(-timeout)
+#                   timeout (when reading).
+#   - Event       - if (not reusing) and pipelined, send the next pipelined
+#                   write.
+# ------------------------------------------------------------------------------
+
+
+# ------------------------------------------------------------------------------
+#  Proc http::AsyncTransaction
+# ------------------------------------------------------------------------------
+# This command is called by geturl and ReplayCore to prepare the HTTP
+# transaction prescribed by a suitably prepared token.
+#
+# Arguments:
+# token         - connection token (name of an array)
+#
+# Return Value: none
+# ------------------------------------------------------------------------------
+
+proc http::AsyncTransaction {token} {
+    variable $token
+    upvar 0 $token state
+    set tk [namespace tail $token]
+
+    variable socketMapping
+    variable socketRdState
+    variable socketWrState
+    variable socketRdQueue
+    variable socketWrQueue
+    variable socketPhQueue
+    variable socketClosing
+    variable socketPlayCmd
+    variable socketCoEvent
+
+    set sock $state(sock)
 
     # See comments above re the start of this timeout in other cases.
     if {(!$state(reusing)) && ($state(-timeout) > 0)} {
@@ -1143,29 +1388,192 @@ proc http::geturl {url args} {
 		[list http::reset $token timeout]]
     }
 
-    if {![info exists sock]} {
-	# Pass -myaddr directly to the socket command
-	if {[info exists state(-myaddr)]} {
-	    lappend sockopts -myaddr $state(-myaddr)
-	}
+    if {    $state(-keepalive)
+	 && (![info exists socketMapping($state(socketinfo))])
+    } {
+	# This code is executed only for the first -keepalive request on a
+	# socket.  It makes the socket persistent.
+	##Log "  PreparePersistentConnection" $token -- $sock -- DO
+        set DoLater [PreparePersistentConnection $token]
+    } else {
+        ##Log "  PreparePersistentConnection" $token -- $sock -- SKIP
+        set DoLater {-traceread 0 -tracewrite 0}
+    }
+
+    if {$state(ReusingPlaceholder)} {
+        # - This request was added to the socketPhQueue of a persistent
+        #   connection.
+        # - But the connection has not yet been created and is a placeholder;
+        # - And the placeholder was created by an earlier request.
+        # - When that earlier request calls OpenSocket, its placeholder is
+        #   replaced with a true socket, and it then executes the equivalent of
+        #   OpenSocket for any subsequent requests that have
+        #   $state(ReusingPlaceholder).
+        Log >J$tk after idle coro NO - ReusingPlaceholder
+    } elseif {$state(alreadyQueued)} {
+        # - This request was added to the socketWrQueue and socketPlayCmd
+        #   of a persistent connection that will close at the end of its current
+        #   read operation.
+        Log >J$tk after idle coro NO - alreadyQueued
+    } else {
+        Log >J$tk after idle coro YES
+        set CoroName ${token}--SocketCoroutine
+        set cancel [after idle [list coroutine $CoroName ::http::OpenSocket \
+                $token $DoLater]]
+        dict set socketCoEvent($state(socketinfo)) $token $cancel
+        set state(socketcoro) $cancel
+    }
+
+    return
+}
+
+
+# ------------------------------------------------------------------------------
+#  Proc http::PreparePersistentConnection
+# ------------------------------------------------------------------------------
+# This command is called by AsyncTransaction to initialise a "persistent
+# connection" based upon a socket placeholder.  It is called the first time the
+# socket is associated with a "-keepalive" request.
+#
+# Arguments:
+# token         - connection token (name of an array)
+#
+# Return Value: - DoLater, a dictionary of boolean values listing unfinished
+#                 tasks; to be passed to ConfigureNewSocket via OpenSocket.
+# ------------------------------------------------------------------------------
+
+proc http::PreparePersistentConnection {token} {
+    variable $token
+    upvar 0 $token state
+
+    variable socketMapping
+    variable socketRdState
+    variable socketWrState
+    variable socketRdQueue
+    variable socketWrQueue
+    variable socketPhQueue
+    variable socketClosing
+    variable socketPlayCmd
+    variable socketCoEvent
+
+    set DoLater {-traceread 0 -tracewrite 0}
+    set socketMapping($state(socketinfo)) $state(sock)
+
+    if {![info exists socketRdState($state(socketinfo))]} {
+        set socketRdState($state(socketinfo)) {}
+        # set varName ::http::socketRdState($state(socketinfo))
+        # trace add variable $varName unset ::http::CancelReadPipeline
+        dict set DoLater -traceread 1
+    }
+    if {![info exists socketWrState($state(socketinfo))]} {
+        set socketWrState($state(socketinfo)) {}
+        # set varName ::http::socketWrState($state(socketinfo))
+        # trace add variable $varName unset ::http::CancelWritePipeline
+        dict set DoLater -tracewrite 1
+    }
+
+    if {$state(-pipeline)} {
+        #Log new, init for pipelined, GRANT write access to $token in geturl
+        # Also grant premature read access to the socket. This is OK.
+        set socketRdState($state(socketinfo)) $token
+        set socketWrState($state(socketinfo)) $token
+    } else {
+        # socketWrState is not used by this non-pipelined transaction.
+        # We cannot leave it as "Wready" because the next call to
+        # http::geturl with a pipelined transaction would conclude that the
+        # socket is available for writing.
+        #Log new, init for nonpipeline, GRANT r/w access to $token in geturl
+        set socketRdState($state(socketinfo)) $token
+        set socketWrState($state(socketinfo)) $token
+    }
+
+    set socketRdQueue($state(socketinfo)) {}
+    set socketWrQueue($state(socketinfo)) {}
+    set socketPhQueue($state(socketinfo)) {}
+    set socketClosing($state(socketinfo)) 0
+    set socketPlayCmd($state(socketinfo)) {ReplayIfClose Wready {} {}}
+    set socketCoEvent($state(socketinfo)) {}
+
+    return $DoLater
+}
+
+# ------------------------------------------------------------------------------
+#  Proc ::http::OpenSocket
+# ------------------------------------------------------------------------------
+# This command is called as a coroutine idletask to start the asynchronous HTTP
+# transaction in most cases.  For the exceptions, see the calling code in
+# command AsyncTransaction.
+#
+# Arguments:
+# token       - connection token (name of an array)
+# DoLater     - dictionary of boolean values listing unfinished tasks
+#
+# Return Value: none
+# ------------------------------------------------------------------------------
+
+proc http::OpenSocket {token DoLater} {
+    variable $token
+    upvar 0 $token state
+    set tk [namespace tail $token]
+
+    variable socketMapping
+    variable socketRdState
+    variable socketWrState
+    variable socketRdQueue
+    variable socketWrQueue
+    variable socketPhQueue
+    variable socketClosing
+    variable socketPlayCmd
+    variable socketCoEvent
+
+    Log >K$tk Start OpenSocket coroutine
+
+    if {![info exists state(-keepalive)]} {
+        # The request has already been cancelled by the calling script.
+        return
+    }
+
+    set sockOld $state(sock)
+
+    dict unset socketCoEvent($state(socketinfo)) $token
+    unset -nocomplain state(socketcoro)
+
+    set reusing $state(reusing)
+
+    if {$reusing} {
+	# If ($reusing) is true, then we do not need to create a new socket,
+	# even if $sockOld is only a placeholder for a socket.
+        set sock $sockOld
+    } else {
+	# set sock in the [catch] below.
 	set pre [clock milliseconds]
 	##Log pre socket opened, - token $token
-	##Log [concat $defcmd $sockopts $targetAddr] - token $token
-	if {[catch {eval $defcmd $sockopts $targetAddr} sock errdict]} {
+	##Log $state(openCmd) - token $token
+	if {[catch {eval $state(openCmd)} sock errdict]} {
+	    # ERROR CASE
 	    # Something went wrong while trying to establish the connection.
-	    # Clean up after events and such, but DON'T call the command
-	    # callback (if available) because we're going to throw an
-	    # exception from here instead.
+	    # Tidy up after events and such, but DON'T call the command
+	    # callback (if available).
+	    # - When this was inline code in http::geturl, it threw an exception
+	    #   from here instead.
+	    # - Now that this code is called from geturl as an idletask and not
+	    #   as inline code, it is inappropriate to run cleanup or throw an
+	    #   exception.  Instead do a normal return, and let Finish report
+	    #   the error using token/state and the -command callback.
+	    #   Finish also undoes PreparePersistentConnection.
 
 	    set state(sock) NONE
-	    Finish $token $sock 1
-	    cleanup $token
-	    dict unset errdict -level
-	    return -options $errdict $sock
+	    set ::errorInfo [dict get $errdict -errorinfo]
+	    set ::errorCode [dict get $errdict -errorcode]
+	    Finish $token $sock
+	    # cleanup $token
+	    return
 	} else {
+	    # Normal return from $state(openCmd) always returns a valid socket.
 	    # Initialisation of a new socket.
 	    ##Log post socket opened, - token $token
 	    ##Log socket opened, now fconfigure - token $token
+	    set state(sock) $sock
 	    set delay [expr {[clock milliseconds] - $pre}]
 	    if {$delay > 3000} {
 		Log socket delay $delay - token $token
@@ -1175,83 +1583,221 @@ proc http::geturl {url args} {
 	    ##Log socket opened, DONE fconfigure - token $token
 	}
     }
-    # Command [socket] is called with -async, but takes 5s to 5.1s to return,
-    # with probability of order 1 in 10,000.  This may be a bizarre scheduling
-    # issue with my (KJN's) system (Fedora Linux).
-    # This does not cause a problem (unless the request times out when this
-    # command returns).
 
-    set state(sock) $sock
     Log "Using $sock for $state(socketinfo) - token $token" \
 	[expr {$state(-keepalive)?"keepalive":""}]
 
-    if {    $state(-keepalive)
-	 && (![info exists socketMapping($state(socketinfo))])
-    } {
-	# Freshly-opened socket that we would like to become persistent.
-	set socketMapping($state(socketinfo)) $sock
+    # Code above has set state(sock) $sock
+    ConfigureNewSocket $token $sockOld $DoLater
+
+    ##Log Leaving http::OpenSocket coroutine [info coroutine] - token $token
+    return
+}
+
+
+# ------------------------------------------------------------------------------
+#  Proc ::http::ConfigureNewSocket
+# ------------------------------------------------------------------------------
+# Command to initialise a newly-created socket.  Called only from OpenSocket.
+#
+# This command is called by OpenSocket whenever a genuine socket (sockNew) has
+# been opened for for use by HTTP.  It does two things:
+# (1) If $token uses a placeholder socket, this command replaces the placeholder
+#     socket with the real socket, not only in $token but in all other requests
+#     that use the same placeholder.
+# (2) It calls ScheduleRequest to schedule each request that uses the socket.
+# 
+#
+# Value of sockOld/sockNew can be "sock" (genuine socket) or "ph" (placeholder).
+# sockNew is ${token}(sock)
+# sockOld   sockNew  CASES
+#  sock       sock   (if $reusing, and sockOld is sock)
+#  ph         sock   (if (not $reusing), and sockOld is ph)
+#  ph         ph     (if $reusing, and sockOld is ph) - not called in this case
+#  sock       ph     (cannot occur unless a bug)      - not called in this case
+#                    (if (not $reusing), and sockOld is sock) - illogical
+#
+# Arguments:
+# token         - connection token (name of an array)
+# sockOld       - handle or placeholder used for a socket before the call to OpenSocket
+# DoLater       - dictionary of boolean values listing unfinished tasks
+#
+# Return Value: none
+# ------------------------------------------------------------------------------
+
+proc http::ConfigureNewSocket {token sockOld DoLater} {
+    variable $token
+    upvar 0 $token state
+    set tk [namespace tail $token]
+
+    variable socketMapping
+    variable socketRdState
+    variable socketWrState
+    variable socketRdQueue
+    variable socketWrQueue
+    variable socketPhQueue
+    variable socketClosing
+    variable socketPlayCmd
+    variable socketCoEvent
+
+    set reusing $state(reusing)
+    set sock $state(sock)
+    ##Log "  ConfigureNewSocket" $token $sockOld ... -- $sock
 
-	if {![info exists socketRdState($state(socketinfo))]} {
-	    set socketRdState($state(socketinfo)) {}
+    if {(!$reusing) && ($sock ne $sockOld)} {
+        # Replace the placeholder value sockOld with sock.
+
+        if {    [info exists socketMapping($state(socketinfo))]
+             && ($socketMapping($state(socketinfo)) eq $sockOld)
+        } {
+            set socketMapping($state(socketinfo)) $sock
+            ##Log set socketMapping($state(socketinfo)) $sock
+        }
+
+        # Now finish any tasks left over from PreparePersistentConnection on
+        # the connection.
+        #
+        # The "unset" traces are fired by init (clears entire arrays), and
+        # by http::Unset.
+        # Unset is called by CloseQueuedQueries and (possibly never) by geturl.
+        #
+        # CancelReadPipeline, CancelWritePipeline call http::Finish for each
+        # token.
+        #
+        # FIXME If Finish is placeholder-aware, these traces can be set earlier,
+        # in PreparePersistentConnection.
+    
+        if {[dict get $DoLater -traceread]} {
 	    set varName ::http::socketRdState($state(socketinfo))
 	    trace add variable $varName unset ::http::CancelReadPipeline
-	}
-	if {![info exists socketWrState($state(socketinfo))]} {
-	    set socketWrState($state(socketinfo)) {}
+        }
+        if {[dict get $DoLater -tracewrite]} {
 	    set varName ::http::socketWrState($state(socketinfo))
 	    trace add variable $varName unset ::http::CancelWritePipeline
-	}
+        }
+    }
 
-	if {$state(-pipeline)} {
-	    #Log new, init for pipelined, GRANT write access to $token in geturl
-	    # Also grant premature read access to the socket. This is OK.
-	    set socketRdState($state(socketinfo)) $token
-	    set socketWrState($state(socketinfo)) $token
-	} else {
-	    # socketWrState is not used by this non-pipelined transaction.
-	    # We cannot leave it as "Wready" because the next call to
-	    # http::geturl with a pipelined transaction would conclude that the
-	    # socket is available for writing.
-	    #Log new, init for nonpipeline, GRANT r/w access to $token in geturl
-	    set socketRdState($state(socketinfo)) $token
-	    set socketWrState($state(socketinfo)) $token
-	}
+    # Do this in all cases.
+    ScheduleRequest $token
 
-	set socketRdQueue($state(socketinfo)) {}
-	set socketWrQueue($state(socketinfo)) {}
-	set socketClosing($state(socketinfo)) 0
-	set socketPlayCmd($state(socketinfo)) {ReplayIfClose Wready {} {}}
-    }
+    # Now look at all other tokens that use the placeholder $sockOld.
+    if {    (!$reusing)
+         && ($sock ne $sockOld)
+         && [info exists socketPhQueue($sockOld)]
+    } {
+        ##Log "  ConfigureNewSocket" $token scheduled, now do $socketPhQueue($sockOld)
+        foreach tok $socketPhQueue($sockOld) {
+	    # 1. Amend the token's (sock).
+	    ##Log set ${tok}(sock) $sock
+	    set ${tok}(sock) $sock
 
-    if {![info exists phost]} {
-	set phost ""
-    }
-    if {$reusing} {
-	# For use by http::ReplayIfDead if the persistent connection has died.
-	# Also used by NextPipelinedWrite.
-	set state(tmpConnArgs) [list $proto $phost $srvurl]
+	    # 2. Schedule the token's HTTP request.
+	    # Every token in socketPhQueue(*) has reusing 1 alreadyQueued 0.
+	    set ${tok}(reusing) 1
+	    set ${tok}(alreadyQueued) 0
+	    ScheduleRequest $tok
+	}
+	set socketPhQueue($sockOld) {}
     }
+    ##Log "  ConfigureNewSocket" $token DONE
 
-    # The element socketWrState($connId) has a value which is either the name of
-    # the token that is permitted to write to the socket, or "Wready" if no
-    # token is permitted to write.
-    #
-    # The code that sets the value to Wready immediately calls
-    # http::NextPipelinedWrite, which examines socketWrQueue($connId) and
-    # processes the next request in the queue, if there is one.  The value
-    # Wready is not found when the interpreter is in the event loop unless the
-    # socket is idle.
-    #
-    # The element socketRdState($connId) has a value which is either the name of
-    # the token that is permitted to read from the socket, or "Rready" if no
-    # token is permitted to read.
-    #
-    # The code that sets the value to Rready then examines
-    # socketRdQueue($connId) and processes the next request in the queue, if
-    # there is one.  The value Rready is not found when the interpreter is in
-    # the event loop unless the socket is idle.
+    return
+}
+
+
+# ------------------------------------------------------------------------------
+# The values of array variables socketMapping etc.
+# ------------------------------------------------------------------------------
+# connId                 "$host:$port"
+# socketMapping($connId) the handle or placeholder for the socket that is used
+#                        for "-keepalive 1" requests to $connId.
+# socketRdState($connId) the token that is currently reading from the socket.
+#                        Other values: Rready (ready for next token to read).
+# socketWrState($connId) the token that is currently writing to the socket.
+#                        Other values: Wready (ready for next token to write),
+#                        peNding (would be ready for next write, except that
+#                        the integrity of a non-pipelined transaction requires
+#                        waiting until the read(s) in progress are finished).
+# socketRdQueue($connId) List of tokens that are queued for reading later.
+# socketWrQueue($connId) List of tokens that are queued for writing later.
+# socketPhQueue($connId) List of tokens that are queued to use a placeholder
+#                        socket, when the real socket has not yet been created.
+# socketClosing($connId) (boolean) true iff a server response header indicates
+#                        that the server will close the connection at the end of
+#                        the current response.
+# socketPlayCmd($connId) The command to execute to replay pending and
+#                        part-completed transactions if the socket closes early.
+# socketCoEvent($connId) Identifier for the "after idle" event that will launch
+#                        an OpenSocket coroutine to open or re-use a socket.
+# ------------------------------------------------------------------------------
+
+
+# ------------------------------------------------------------------------------
+# Using socketWrState(*), socketWrQueue(*), socketRdState(*), socketRdQueue(*)
+# ------------------------------------------------------------------------------
+# The element socketWrState($connId) has a value which is either the name of
+# the token that is permitted to write to the socket, or "Wready" if no
+# token is permitted to write.
+#
+# The code that sets the value to Wready immediately calls
+# http::NextPipelinedWrite, which examines socketWrQueue($connId) and
+# processes the next request in the queue, if there is one.  The value
+# Wready is not found when the interpreter is in the event loop unless the
+# socket is idle.
+#
+# The element socketRdState($connId) has a value which is either the name of
+# the token that is permitted to read from the socket, or "Rready" if no
+# token is permitted to read.
+#
+# The code that sets the value to Rready then examines
+# socketRdQueue($connId) and processes the next request in the queue, if
+# there is one.  The value Rready is not found when the interpreter is in
+# the event loop unless the socket is idle.
+# ------------------------------------------------------------------------------
+
+
+# ------------------------------------------------------------------------------
+#  Proc http::ScheduleRequest
+# ------------------------------------------------------------------------------
+# Command to either begin the HTTP request, or add it to the appropriate queue.
+# Called from two places in ConfigureNewSocket.
+#
+# Arguments:
+# token         - connection token (name of an array)
+#
+# Return Value: none
+# ------------------------------------------------------------------------------
+
+proc http::ScheduleRequest {token} {
+    variable $token
+    upvar 0 $token state
+    set tk [namespace tail $token]
+
+    Log >L$tk ScheduleRequest
+
+    variable socketMapping
+    variable socketRdState
+    variable socketWrState
+    variable socketRdQueue
+    variable socketWrQueue
+    variable socketPhQueue
+    variable socketClosing
+    variable socketPlayCmd
+    variable socketCoEvent
+
+    set Unfinished 0
+
+    set reusing $state(reusing)
+    set sockNew $state(sock)
 
-    if {$alreadyQueued} {
+    # The "if" tests below: must test against the current values of
+    # socketWrState, socketRdState, and so the tests must be done here,
+    # not earlier in PreparePersistentConnection.
+
+    if {$state(alreadyQueued)} {
+	# The request has been appended to the queue of a persistent socket
+	# (that is scheduled to close and have its queue replayed).
+	#
 	# A write may or may not be in progress.  There is no need to set
 	# socketWrState to prevent another call stealing write access - all
 	# subsequent calls on this socket will come here because the socket
@@ -1284,55 +1830,56 @@ proc http::geturl {url args} {
 	# pipelined request jumping the queue.
 	##Log "HTTP request for token $token is queued for nonpipeline use"
 	#Log re-use nonpipeline, GRANT delayed write access to $token in geturl
-
 	set socketWrState($state(socketinfo)) peNding
 	lappend socketWrQueue($state(socketinfo)) $token
 
     } else {
-	if {$reusing && $state(-pipeline)} {
-	    #Log re-use pipelined, GRANT write access to $token in geturl
-	    set socketWrState($state(socketinfo)) $token
-
-	} elseif {$reusing} {
-	    # Cf tests above - both are ready.
-	    #Log re-use nonpipeline, GRANT r/w access to $token in geturl
-	    set socketRdState($state(socketinfo)) $token
-	    set socketWrState($state(socketinfo)) $token
-	}
-
-	# All (!$reusing) cases come here, and also some $reusing cases if the
-	# connection is ready.
+        if {$reusing && $state(-pipeline)} {
+	    #Log new, init for pipelined, GRANT write access to $token in geturl
+	    # DO NOT grant premature read access to the socket.
+            # set socketRdState($state(socketinfo)) $token
+            set socketWrState($state(socketinfo)) $token
+        } elseif {$reusing} {
+	    # socketWrState is not used by this non-pipelined transaction.
+	    # We cannot leave it as "Wready" because the next call to
+	    # http::geturl with a pipelined transaction would conclude that the
+	    # socket is available for writing.
+	    #Log new, init for nonpipeline, GRANT r/w access to $token in geturl
+            set socketRdState($state(socketinfo)) $token
+            set socketWrState($state(socketinfo)) $token
+        } else {
+        }
+
+	# Process the request now.
+	# - Command is not called unless $state(sock) is a real socket handle
+	#   and not a placeholder.
+	# - All (!$reusing) cases come here.
+	# - Some $reusing cases come here too if the connection is
+	#   marked as ready.  Those $reusing cases are:
+	#   $reusing && ($socketWrState($state(socketinfo)) eq "Wready") &&
+	#   EITHER !$pipeline && ($socketRdState($state(socketinfo)) eq "Rready")
+	#   OR      $pipeline
+	#
 	#Log ---- $state(socketinfo) << conn to $token for HTTP request (a)
+	##Log "  ScheduleRequest" $token -- fileevent $state(sock) writable for $token
 	# Connect does its own fconfigure.
-	fileevent $sock writable \
-		[list http::Connect $token $proto $phost $srvurl]
-    }
 
-    # Wait for the connection to complete.
-    if {![info exists state(-command)]} {
-	# geturl does EVERYTHING asynchronously, so if the user
-	# calls it synchronously, we just do a wait here.
-	http::wait $token
+        lassign $state(connArgs) proto phost srvurl
 
-	if {![info exists state]} {
-	    # If we timed out then Finish has been called and the users
-	    # command callback may have cleaned up the token. If so we end up
-	    # here with nothing left to do.
-	    return $token
-	} elseif {$state(status) eq "error"} {
-	    # Something went wrong while trying to establish the connection.
-	    # Clean up after events and such, but DON'T call the command
-	    # callback (if available) because we're going to throw an
-	    # exception from here instead.
-	    set err [lindex $state(error) 0]
-	    cleanup $token
-	    return -code error $err
+	if {[catch {
+		fileevent $state(sock) writable \
+			[list http::Connect $token $proto $phost $srvurl]
+	} res opts]} {
+	    # The socket no longer exists.
+	    ##Log bug -- socket gone -- $res -- $opts
 	}
+
     }
-    ##Log Leaving http::geturl - token $token
-    return $token
+
+    return
 }
 
+
 # http::Connected --
 #
 #	Callback used when the connection to the HTTP server is actually
@@ -1354,8 +1901,10 @@ proc http::Connected {token proto phost srvurl} {
     variable socketWrState
     variable socketRdQueue
     variable socketWrQueue
+    variable socketPhQueue
     variable socketClosing
     variable socketPlayCmd
+    variable socketCoEvent
 
     variable $token
     upvar 0 $token state
@@ -1601,6 +2150,7 @@ proc http::Connected {token proto phost srvurl} {
 	    Finish $token $err
 	}
     }
+    return
 }
 
 # http::registerError
@@ -1646,8 +2196,10 @@ proc http::DoneRequest {token} {
     variable socketWrState
     variable socketRdQueue
     variable socketWrQueue
+    variable socketPhQueue
     variable socketClosing
     variable socketPlayCmd
+    variable socketCoEvent
 
     variable $token
     upvar 0 $token state
@@ -1706,6 +2258,7 @@ proc http::DoneRequest {token} {
 	# In the nonpipeline case, connection for reading always occurs.
 	ReceiveResponse $token
     }
+    return
 }
 
 # http::ReceiveResponse
@@ -1724,11 +2277,11 @@ proc http::ReceiveResponse {token} {
 		     -buffersize $state(-blocksize)
     Log ^D$tk begin receiving response - token $token
 
-    coroutine ${token}EventCoroutine http::Event $sock $token
+    coroutine ${token}--EventCoroutine http::Event $sock $token
     if {[info exists state(-handler)] || [info exists state(-progress)]} {
         fileevent $sock readable [list http::EventGateway $sock $token]
     } else {
-        fileevent $sock readable ${token}EventCoroutine
+        fileevent $sock readable ${token}--EventCoroutine
     }
     return
 }
@@ -1752,8 +2305,8 @@ proc http::EventGateway {sock token} {
     variable $token
     upvar 0 $token state
     fileevent $sock readable {}
-    catch {${token}EventCoroutine} res opts
-    if {[info commands ${token}EventCoroutine] ne {}} {
+    catch {${token}--EventCoroutine} res opts
+    if {[info commands ${token}--EventCoroutine] ne {}} {
         # The coroutine can be deleted by completion (a non-yield return), by
         # http::Finish (when there is a premature end to the transaction), by
         # http::reset or http::cleanup, or if the caller set option -channel
@@ -1821,7 +2374,7 @@ proc http::NextPipelinedWrite {token} {
     } {
 	# - The usual case for a pipelined connection, ready for a new request.
 	#Log pipelined, GRANT write access to $token2 in NextPipelinedWrite
-	set conn [set ${token2}(tmpConnArgs)]
+	set conn [set ${token2}(connArgs)]
 	set socketWrState($connId) $token2
 	set socketWrQueue($connId) [lrange $socketWrQueue($connId) 1 end]
 	# Connect does its own fconfigure.
@@ -1846,9 +2399,7 @@ proc http::NextPipelinedWrite {token} {
 	# The case in which the next request will be non-pipelined, and the read
 	# and write queues is ready: which is the condition for a non-pipelined
 	# write.
-	variable $token3
-	upvar 0 $token3 state3
-	set conn [set ${token3}(tmpConnArgs)]
+	set conn [set ${token3}(connArgs)]
 	#Log nonpipeline, GRANT r/w access to $token3 in NextPipelinedWrite
 	set socketRdState($connId) $token3
 	set socketWrState($connId) $token3
@@ -1880,6 +2431,7 @@ proc http::NextPipelinedWrite {token} {
 	#Log re-use nonpipeline, GRANT delayed write access to $token in NextP..
 	set socketWrState($connId) peNding
     }
+    return
 }
 
 # http::CancelReadPipeline
@@ -1912,6 +2464,7 @@ proc http::CancelReadPipeline {name1 connId op} {
 	}
 	set socketRdQueue($connId) {}
     }
+    return
 }
 
 # http::CancelWritePipeline
@@ -1945,6 +2498,7 @@ proc http::CancelWritePipeline {name1 connId op} {
 	}
 	set socketWrQueue($connId) {}
     }
+    return
 }
 
 # http::ReplayIfDead --
@@ -1967,19 +2521,21 @@ proc http::CancelWritePipeline {name1 connId op} {
 # Side Effects:
 #	Use the same token, but try to open a new socket.
 
-proc http::ReplayIfDead {tokenArg doing} {
+proc http::ReplayIfDead {token doing} {
     variable socketMapping
     variable socketRdState
     variable socketWrState
     variable socketRdQueue
     variable socketWrQueue
+    variable socketPhQueue
     variable socketClosing
     variable socketPlayCmd
+    variable socketCoEvent
 
-    variable $tokenArg
-    upvar 0 $tokenArg stateArg
+    variable $token
+    upvar 0 $token state
 
-    Log running http::ReplayIfDead for $tokenArg $doing
+    Log running http::ReplayIfDead for $token $doing
 
     # 1. Merge the tokens for transactions in flight, the read (response) queue,
     #    and the write (request) queue.
@@ -1988,85 +2544,86 @@ proc http::ReplayIfDead {tokenArg doing} {
     set InFlightW {}
 
     # Obtain the tokens for transactions in flight.
-    if {$stateArg(-pipeline)} {
+    if {$state(-pipeline)} {
 	# Two transactions may be in flight.  The "read" transaction was first.
 	# It is unlikely that the server would close the socket if a response
 	# was pending; however, an earlier request (as well as the present
 	# request) may have been sent and ignored if the socket was half-closed
 	# by the server.
 
-	if {    [info exists socketRdState($stateArg(socketinfo))]
-	     && ($socketRdState($stateArg(socketinfo)) ne "Rready")
+	if {    [info exists socketRdState($state(socketinfo))]
+	     && ($socketRdState($state(socketinfo)) ne "Rready")
 	} {
-	    lappend InFlightR $socketRdState($stateArg(socketinfo))
+	    lappend InFlightR $socketRdState($state(socketinfo))
 	} elseif {($doing eq "read")} {
-	    lappend InFlightR $tokenArg
+	    lappend InFlightR $token
 	}
 
-	if {    [info exists socketWrState($stateArg(socketinfo))]
-	     && $socketWrState($stateArg(socketinfo)) ni {Wready peNding}
+	if {    [info exists socketWrState($state(socketinfo))]
+	     && $socketWrState($state(socketinfo)) ni {Wready peNding}
 	} {
-	    lappend InFlightW $socketWrState($stateArg(socketinfo))
+	    lappend InFlightW $socketWrState($state(socketinfo))
 	} elseif {($doing eq "write")} {
-	    lappend InFlightW $tokenArg
+	    lappend InFlightW $token
 	}
 
-	# Report any inconsistency of $tokenArg with socket*state.
+	# Report any inconsistency of $token with socket*state.
 	if {    ($doing eq "read")
-	     && [info exists socketRdState($stateArg(socketinfo))]
-	     && ($tokenArg ne $socketRdState($stateArg(socketinfo)))
+	     && [info exists socketRdState($state(socketinfo))]
+	     && ($token ne $socketRdState($state(socketinfo)))
 	} {
-	    Log WARNING - ReplayIfDead pipelined tokenArg $tokenArg $doing \
-		    ne socketRdState($stateArg(socketinfo)) \
-		      $socketRdState($stateArg(socketinfo))
+	    Log WARNING - ReplayIfDead pipelined token $token $doing \
+		    ne socketRdState($state(socketinfo)) \
+		      $socketRdState($state(socketinfo))
 
 	} elseif {
 		($doing eq "write")
-	     && [info exists socketWrState($stateArg(socketinfo))]
-	     && ($tokenArg ne $socketWrState($stateArg(socketinfo)))
+	     && [info exists socketWrState($state(socketinfo))]
+	     && ($token ne $socketWrState($state(socketinfo)))
 	} {
-	    Log WARNING - ReplayIfDead pipelined tokenArg $tokenArg $doing \
-		    ne socketWrState($stateArg(socketinfo)) \
-		      $socketWrState($stateArg(socketinfo))
+	    Log WARNING - ReplayIfDead pipelined token $token $doing \
+		    ne socketWrState($state(socketinfo)) \
+		      $socketWrState($state(socketinfo))
 	}
     } else {
 	# One transaction should be in flight.
 	# socketRdState, socketWrQueue are used.
 	# socketRdQueue should be empty.
 
-	# Report any inconsistency of $tokenArg with socket*state.
-	if {$tokenArg ne $socketRdState($stateArg(socketinfo))} {
-	    Log WARNING - ReplayIfDead nonpipeline tokenArg $tokenArg $doing \
-		    ne socketRdState($stateArg(socketinfo)) \
-		      $socketRdState($stateArg(socketinfo))
+	# Report any inconsistency of $token with socket*state.
+	if {$token ne $socketRdState($state(socketinfo))} {
+	    Log WARNING - ReplayIfDead nonpipeline token $token $doing \
+		    ne socketRdState($state(socketinfo)) \
+		      $socketRdState($state(socketinfo))
 	}
 
 	# Report the inconsistency that socketRdQueue is non-empty.
-	if {    [info exists socketRdQueue($stateArg(socketinfo))]
-	     && ($socketRdQueue($stateArg(socketinfo)) ne {})
+	if {    [info exists socketRdQueue($state(socketinfo))]
+	     && ($socketRdQueue($state(socketinfo)) ne {})
 	} {
-	    Log WARNING - ReplayIfDead nonpipeline tokenArg $tokenArg $doing \
-		    has read queue socketRdQueue($stateArg(socketinfo)) \
-		    $socketRdQueue($stateArg(socketinfo)) ne {}
+	    Log WARNING - ReplayIfDead nonpipeline token $token $doing \
+		    has read queue socketRdQueue($state(socketinfo)) \
+		    $socketRdQueue($state(socketinfo)) ne {}
 	}
 
-	lappend InFlightW $socketRdState($stateArg(socketinfo))
-	set socketRdQueue($stateArg(socketinfo)) {}
+	lappend InFlightW $socketRdState($state(socketinfo))
+	set socketRdQueue($state(socketinfo)) {}
     }
 
     set newQueue {}
     lappend newQueue {*}$InFlightR
-    lappend newQueue {*}$socketRdQueue($stateArg(socketinfo))
+    lappend newQueue {*}$socketRdQueue($state(socketinfo))
     lappend newQueue {*}$InFlightW
-    lappend newQueue {*}$socketWrQueue($stateArg(socketinfo))
+    lappend newQueue {*}$socketWrQueue($state(socketinfo))
 
 
-    # 2. Tidy up tokenArg.  This is a cut-down form of Finish/CloseSocket.
+    # 2. Tidy up token.  This is a cut-down form of Finish/CloseSocket.
     #    Do not change state(status).
-    #    No need to after cancel stateArg(after) - either this is done in
+    #    No need to after cancel state(after) - either this is done in
     #    ReplayCore/ReInit, or Finish is called.
 
-    catch {close $stateArg(sock)}
+    catch {close $state(sock)}
+    Unset $state(socketinfo)
 
     # 2a. Tidy the tokens in the queues - this is done in ReplayCore/ReInit.
     # - Transactions, if any, that are awaiting responses cannot be completed.
@@ -2078,6 +2635,7 @@ proc http::ReplayIfDead {tokenArg doing} {
     #   to new values in ReplayCore.
 
     ReplayCore $newQueue
+    return
 }
 
 # http::ReplayIfClose --
@@ -2108,7 +2666,7 @@ proc http::ReplayIfClose {Wstate Rqueue Wqueue} {
     if {$Wstate ni {Wready peNding}} {
 	lappend InFlightW $Wstate
     }
-
+    ##Log $Rqueue -- $InFlightW -- $Wqueue
     set newQueue {}
     lappend newQueue {*}$Rqueue
     lappend newQueue {*}$InFlightW
@@ -2117,6 +2675,7 @@ proc http::ReplayIfClose {Wstate Rqueue Wqueue} {
     # 2. Cleanup - none needed, done by the caller.
 
     ReplayCore $newQueue
+    return
 }
 
 # http::ReInit --
@@ -2160,6 +2719,11 @@ proc http::ReInit {token} {
 	after cancel $state(after)
 	unset state(after)
     }
+    if {[info exists state(socketcoro)]} {
+        Log $token Cancel socket after-idle event (ReInit)
+        after cancel $state(socketcoro)
+        unset state(socketcoro)
+    }
 
     # Don't alter state(status) - this would trigger http::wait if it is in use.
     set tmpState    $state(tmpState)
@@ -2199,13 +2763,17 @@ proc http::ReInit {token} {
 #	Use existing tokens, but try to open a new socket.
 
 proc http::ReplayCore {newQueue} {
+    variable TmpSockCounter
+
     variable socketMapping
     variable socketRdState
     variable socketWrState
     variable socketRdQueue
     variable socketWrQueue
+    variable socketPhQueue
     variable socketClosing
     variable socketPlayCmd
+    variable socketCoEvent
 
     if {[llength $newQueue] == 0} {
 	# Nothing to do.
@@ -2237,92 +2805,30 @@ proc http::ReplayCore {newQueue} {
     unset state(tmpConnArgs)
 
     set state(reusing) 0
+    set state(ReusingPlaceholder) 0
+    set state(alreadyQueued) 0
 
-    if {$state(-timeout) > 0} {
-	set resetCmd [list http::reset $token timeout]
-	set state(after) [after $state(-timeout) $resetCmd]
-    }
-
-    set pre [clock milliseconds]
-    ##Log pre socket opened, - token $token
-    ##Log $tmpOpenCmd - token $token
-    # 4. Open a socket.
-    if {[catch {eval $tmpOpenCmd} sock]} {
-	# Something went wrong while trying to establish the connection.
-	Log FAILED - $sock
-	set state(sock) NONE
-	Finish $token $sock
-	return
-    }
-    ##Log post socket opened, - token $token
-    set delay [expr {[clock milliseconds] - $pre}]
-    if {$delay > 3000} {
-	Log socket delay $delay - token $token
-    }
-    # Command [socket] is called with -async, but takes 5s to 5.1s to return,
-    # with probability of order 1 in 10,000.  This may be a bizarre scheduling
-    # issue with my (KJN's) system (Fedora Linux).
-    # This does not cause a problem (unless the request times out when this
-    # command returns).
-
-    # 5. Configure the persistent socket data.
-    if {$state(-keepalive)} {
-	set socketMapping($state(socketinfo)) $sock
-
-	if {![info exists socketRdState($state(socketinfo))]} {
-	    set socketRdState($state(socketinfo)) {}
-	    set varName ::http::socketRdState($state(socketinfo))
-	    trace add variable $varName unset ::http::CancelReadPipeline
-	}
-
-	if {![info exists socketWrState($state(socketinfo))]} {
-	    set socketWrState($state(socketinfo)) {}
-	    set varName ::http::socketWrState($state(socketinfo))
-	    trace add variable $varName unset ::http::CancelWritePipeline
-	}
-
-	if {$state(-pipeline)} {
-	    #Log new, init for pipelined, GRANT write acc to $token ReplayCore
-	    set socketRdState($state(socketinfo)) $token
-	    set socketWrState($state(socketinfo)) $token
-	} else {
-	    #Log new, init for nonpipeline, GRANT r/w acc to $token ReplayCore
-	    set socketRdState($state(socketinfo)) $token
-	    set socketWrState($state(socketinfo)) $token
-	}
-
-	set socketRdQueue($state(socketinfo)) {}
-	set socketWrQueue($state(socketinfo)) $newQueue
-	set socketClosing($state(socketinfo)) 0
-	set socketPlayCmd($state(socketinfo)) {ReplayIfClose Wready {} {}}
-    }
+    # Give the socket a placeholder name before it is created.
+    set sock HTTP_PLACEHOLDER_[incr TmpSockCounter]
+    set state(sock) $sock
 
-    ##Log pre newQueue ReInit, - token $token
-    # 6. Configure sockets in the queue.
+    # Move the $newQueue into the placeholder socket's socketPhQueue.
+    set socketPhQueue($sock) {}
     foreach tok $newQueue {
 	if {[ReInit $tok]} {
 	    set ${tok}(reusing) 1
 	    set ${tok}(sock) $sock
+	    lappend socketPhQueue($sock) $tok
 	} else {
 	    set ${tok}(reusing) 1
 	    set ${tok}(sock) NONE
-	    Finish $token {cannot send this request again}
+	    Finish $tok {cannot send this request again}
 	}
     }
 
-    # 7. Configure the socket for newToken to send a request.
-    set state(sock) $sock
-    Log "Using $sock for $state(socketinfo) - token $token" \
-	[expr {$state(-keepalive)?"keepalive":""}]
-
-    # Initialisation of a new socket.
-    ##Log socket opened, now fconfigure - token $token
-    fconfigure $sock -translation {auto crlf} -buffersize $state(-blocksize)
-    ##Log socket opened, DONE fconfigure - token $token
+    AsyncTransaction $token
 
-    # Connect does its own fconfigure.
-    fileevent $sock writable [list http::Connect $token {*}$tmpConnArgs]
-    #Log ---- $sock << conn to $token for HTTP request (e)
+    return
 }
 
 # Data access functions:
@@ -2374,7 +2880,7 @@ proc http::error {token} {
     if {[info exists state(error)]} {
 	return $state(error)
     }
-    return ""
+    return
 }
 
 # http::cleanup
@@ -2390,16 +2896,25 @@ proc http::error {token} {
 proc http::cleanup {token} {
     variable $token
     upvar 0 $token state
-    if {[info commands ${token}EventCoroutine] ne {}} {
-	rename ${token}EventCoroutine {}
+    if {[info commands ${token}--EventCoroutine] ne {}} {
+	rename ${token}--EventCoroutine {}
+    }
+    if {[info commands ${token}--SocketCoroutine] ne {}} {
+	rename ${token}--SocketCoroutine {}
     }
     if {[info exists state(after)]} {
 	after cancel $state(after)
 	unset state(after)
     }
+    if {[info exists state(socketcoro)]} {
+        Log $token Cancel socket after-idle event (cleanup)
+        after cancel $state(socketcoro)
+        unset state(socketcoro)
+    }
     if {[info exists state]} {
 	unset state
     }
+    return
 }
 
 # http::Connect
@@ -2417,11 +2932,20 @@ proc http::Connect {token proto phost srvurl} {
     variable $token
     upvar 0 $token state
     set tk [namespace tail $token]
-    set err "due to unexpected EOF"
-    if {
-	[eof $state(sock)] ||
-	[set err [fconfigure $state(sock) -error]] ne ""
-    } {
+
+    if {[catch {eof $state(sock)} tmp] || $tmp} {
+        set err "due to unexpected EOF"
+    } elseif {[set err [fconfigure $state(sock) -error]] ne ""} {
+        # set err is done in test
+    } else {
+        # All OK
+	set state(state) connecting
+	fileevent $state(sock) writable {}
+	::http::Connected $token $proto $phost $srvurl
+	return
+    }
+
+    # Error cases.
 	Log "WARNING - if testing, pay special attention to this\
 		case (GJ) which is seldom executed - token $token"
 	if {[info exists state(reusing)] && $state(reusing)} {
@@ -2438,11 +2962,7 @@ proc http::Connect {token proto phost srvurl} {
 	    # be discarded.
 	}
 	Finish $token "connect failed $err"
-    } else {
-	set state(state) connecting
-	fileevent $state(sock) writable {}
-	::http::Connected $token $proto $phost $srvurl
-    }
+    return
 }
 
 # http::Write
@@ -2462,8 +2982,10 @@ proc http::Write {token} {
     variable socketWrState
     variable socketRdQueue
     variable socketWrQueue
+    variable socketPhQueue
     variable socketClosing
     variable socketPlayCmd
+    variable socketCoEvent
 
     variable $token
     upvar 0 $token state
@@ -2547,12 +3069,13 @@ proc http::Write {token} {
 	eval $state(-queryprogress) \
 	    [list $token $state(querylength) $state(queryoffset)]
     }
+    return
 }
 
 # http::Event
 #
 #	Handle input on the socket. This command is the core of
-#	the coroutine commands ${token}EventCoroutine that are
+#	the coroutine commands ${token}--EventCoroutine that are
 #	bound to "fileevent $sock readable" and process input.
 #
 # Arguments
@@ -2569,8 +3092,10 @@ proc http::Event {sock token} {
     variable socketWrState
     variable socketRdQueue
     variable socketWrQueue
+    variable socketPhQueue
     variable socketClosing
     variable socketPlayCmd
+    variable socketCoEvent
 
     variable $token
     upvar 0 $token state
@@ -2581,7 +3106,7 @@ proc http::Event {sock token} {
 
 	if {![info exists state]} {
 	    Log "Event $sock with invalid token '$token' - remote close?"
-	    if {![eof $sock]} {
+	    if {!([catch {eof $sock} tmp] || $tmp)} {
 		if {[set d [read $sock]] ne ""} {
 		    Log "WARNING: additional data left on closed socket\
 			    - token $token"
@@ -2626,7 +3151,7 @@ proc http::Event {sock token} {
 	    } elseif {$nsl >= 0} {
 		##Log - connecting 1 - token $token
 		set state(state) "header"
-	    } elseif {    [eof $sock]
+	    } elseif {    ([catch {eof $sock} tmp] || $tmp)
 		       && [info exists state(reusing)]
 		       && $state(reusing)
 	    } {
@@ -2694,6 +3219,20 @@ proc http::Event {sock token} {
 		    # response.
 		    ##Log WARNING - socket will close after response for $token
 		    # Prepare data for a call to ReplayIfClose.
+		    Log $token socket will close after this transaction
+		    # 1. Cancel socket-assignment coro events that have not yet
+		    # launched, and add the tokens to the write queue.
+		    if {[info exists socketCoEvent($state(socketinfo))]} {
+			foreach {tok can} $socketCoEvent($state(socketinfo)) {
+			    lappend socketWrQueue($state(socketinfo)) $tok
+			    unset -nocomplain ${tok}(socketcoro)
+			    after cancel $can
+			    Log $tok Cancel socket after-idle event (Event)
+			    Log Move $tok from socketCoEvent to socketWrQueue and cancel its after idle coro
+			}
+			set socketCoEvent($state(socketinfo)) {}
+		    }
+
 		    if {    ($socketRdQueue($state(socketinfo)) ne {})
 			 || ($socketWrQueue($state(socketinfo)) ne {})
 			 || ($socketWrState($state(socketinfo)) ni
@@ -2706,7 +3245,6 @@ proc http::Event {sock token} {
 			    set msg "token ${InFlightW} is InFlightW"
 			    ##Log $msg - token $token
 			}
-
 			set socketPlayCmd($state(socketinfo)) \
 				[list ReplayIfClose $InFlightW \
 				$socketRdQueue($state(socketinfo)) \
@@ -2722,14 +3260,16 @@ proc http::Event {sock token} {
 				after cancel [set ${tokenVal}(after)]
 				unset ${tokenVal}(after)
 			    }
+			    # Tokens in the read queue have no (socketcoro) to
+			    # cancel.
 			}
-
 		    } else {
 			set socketPlayCmd($state(socketinfo)) \
 				{ReplayIfClose Wready {} {}}
 		    }
 
-		    # Do not allow further connections on this socket.
+		    # Do not allow further connections on this socket (but
+		    # geturl can add new requests to the replay).
 		    set socketClosing($state(socketinfo)) 1
 		}
 
@@ -2803,7 +3343,7 @@ proc http::Event {sock token} {
 		    if {![info exists state(-handler)]} {
 			# Initiate a sequence of background fcopies.
 			fileevent $sock readable {}
-			rename ${token}EventCoroutine {}
+			rename ${token}--EventCoroutine {}
 			CopyStart $sock $token
 			return
 		    }
@@ -3033,7 +3573,8 @@ proc http::Event {sock token} {
 
 	# catch as an Eot above may have closed the socket already
 	# $state(state) may be connecting, header, body, or complete
-	if {![set cc [catch {eof $sock} eof]] && $eof} {
+	if {(![catch {eof $sock} eof]) && $eof} {
+	    # [eof sock] succeeded and the result was 1
 	    ##Log eof - token $token
 	    if {[info exists $token]} {
 		set state(connection) close
@@ -3055,10 +3596,12 @@ proc http::Event {sock token} {
 		Log ^X$tk end of response (token error) - token $token
 		CloseSocket $sock
 	    }
-	} elseif {$cc} {
-	    return
+	} else {
+	    # EITHER [eof sock] failed - presumed done by Eot
+	    # OR     [eof sock] succeeded and the result was 0
 	}
     }
+    return
 }
 
 # http::TestForReplay
@@ -3228,7 +3771,8 @@ proc http::ParseCookie {token value} {
 # http::getTextLine --
 #
 #	Get one line with the stream in crlf mode.
-#	Used if Transfer-Encoding is chunked.
+#	Used if Transfer-Encoding is chunked, to read the line that
+#	reports the size of the following chunk.
 #	Empty line is not distinguished from eof.  The caller must
 #	be able to handle this.
 #
@@ -3251,6 +3795,8 @@ proc http::getTextLine {sock} {
 #
 #	Replacement for a blocking read.
 #	The caller must be a coroutine.
+#	Used when we expect to read a chunked-encoding
+#	chunk of known size.
 
 proc http::BlockingRead {sock size} {
     if {$size < 1} {
@@ -3260,7 +3806,7 @@ proc http::BlockingRead {sock size} {
     while 1 {
 	set need [expr {$size - [string length $result]}]
 	set block [read $sock $need]
-	set eof [eof $sock]
+	set eof [expr {[catch {eof $sock} tmp] || $tmp}]
 	append result $block
 	if {[string length $result] >= $size || $eof} {
 	    return $result
@@ -3280,7 +3826,7 @@ proc http::BlockingRead {sock size} {
 proc http::BlockingGets {sock} {
     while 1 {
 	set count [gets $sock line]
-	set eof [eof $sock]
+	set eof [expr {[catch {eof $sock} tmp] || $tmp}]
 	if {$count >= 0 || $eof} {
 	    return $line
 	} else {
@@ -3301,7 +3847,7 @@ proc http::BlockingGets {sock} {
 #	This closes the connection upon error
 
 proc http::CopyStart {sock token {initial 1}} {
-    upvar #0 $token state
+    upvar 0 $token state
     if {[info exists state(transfer)] && $state(transfer) eq "chunked"} {
 	foreach coding [ContentEncoding $token] {
 	    lappend state(zlib) [zlib stream $coding]
@@ -3324,6 +3870,7 @@ proc http::CopyStart {sock token {initial 1}} {
 	    Finish $token $err
 	}
     }
+    return
 }
 
 proc http::CopyChunk {token chunk} {
@@ -3353,6 +3900,7 @@ proc http::CopyChunk {token chunk} {
 	}
 	Eot $token ;# FIX ME: pipelining.
     }
+    return
 }
 
 # http::CopyDone
@@ -3383,6 +3931,7 @@ proc http::CopyDone {token count {error {}}} {
     } else {
 	CopyStart $sock $token 0
     }
+    return
 }
 
 # http::Eot
@@ -3452,6 +4001,7 @@ proc http::Eot {token {reason {}}} {
 	}
     }
     Finish $token $reason
+    return
 }
 
 # http::wait --
@@ -3550,6 +4100,8 @@ proc http::ProxyRequired {host} {
 	    set http(-proxyport) 8080
 	}
 	return [list $http(-proxyhost) $http(-proxyport)]
+    } else {
+	return
     }
 }
 
@@ -3698,6 +4250,256 @@ proc http::GetFieldValue {headers fieldName} {
 proc http::make-transformation-chunked {chan command} {
     coroutine [namespace current]::dechunk$chan ::http::ReceiveChunked $chan $command
     chan event $chan readable [namespace current]::dechunk$chan
+    return
+}
+
+
+# ------------------------------------------------------------------------------
+#  Proc http::socket
+# ------------------------------------------------------------------------------
+# This command is a drop-in replacement for ::socket.
+# Arguments and return value as for ::socket.
+#
+# Notes.
+# - http::socket is specified in place of ::socket by the definition of urlTypes
+#   in the namespace header of this file (http.tcl).
+# - The command makes a simple call to ::socket unless the user has called
+#   http::config to change the value of -threadlevel from the default value 0.
+# - For -threadlevel 1 or 2, if the Thread package is available, the command
+#   waits in the event loop while the socket is opened in another thread.  This
+#   is a workaround for bug [824251] - it prevents http::geturl from blocking
+#   the event loop if the DNS lookup or server connection is slow.
+# - FIXME Use a thread pool if connections are very frequent.
+# - FIXME The peer thread can transfer the socket only to the main interpreter
+#   in the present thread.  Therefore this code works only if this script runs
+#   in the main interpreter.  In a child interpreter, the parent must alias a
+#   command to ::http::socket in the child, run http::socket in the parent,
+#   and then transfer the socket to the child.
+# - The http::socket command is simple, and can easily be replaced with an
+#   alternative command that uses a different technique to open a socket while
+#   entering the event loop.
+# ------------------------------------------------------------------------------
+
+proc http::socket {args} {
+    variable ThreadVar
+    variable ThreadCounter
+    variable http
+
+    LoadThreadIfNeeded
+
+    set targ [lsearch -exact $args -token]
+    if {$targ != -1} {
+        set token [lindex $args $targ+1]
+        set args [lreplace $args $targ $targ+1]
+        upvar 0 $token state
+    }
+
+    if {!$http(usingThread)} {
+        # Use plain "::socket".  This is the default.
+        return [eval ::socket $args]
+    }
+
+    set defcmd ::socket
+    set sockargs $args
+    set script "
+        [list proc ::SockInThread {caller defcmd sockargs} [info body http::SockInThread]]
+        [list ::SockInThread [thread::id] $defcmd $sockargs]
+    "
+
+    set state(tid) [thread::create]
+    set varName ::http::ThreadVar([incr ThreadCounter])
+    thread::send -async $state(tid) $script $varName
+    Log >T Thread Start Wait $args -- coro [info coroutine] $varName
+    if {[info coroutine] ne {}} {
+        # All callers in the http package are coroutines launched by
+        # the event loop.
+        # The cwait command requires a coroutine because it yields
+        # to the caller; $varName is traced and the coroutine resumes
+        # when the variable is written.
+        cwait $varName
+    } else {
+        return -code error {code must run in a coroutine}
+        # For testing with a non-coroutine caller outside the http package.
+        # vwait $varName
+    }
+    Log >U Thread End Wait $args -- coro [info coroutine] $varName [set $varName]
+    thread::release $state(tid)
+    set state(tid) {}
+    lassign [set $varName] catchCode errdict sock
+    unset $varName
+    dict set errdict -code $catchCode
+    return -options $errdict $sock
+}
+
+# The commands below are dependencies of http::socket and
+# are not used elsewhere.
+
+# ------------------------------------------------------------------------------
+#  Proc http::LoadThreadIfNeeded
+# ------------------------------------------------------------------------------
+# Command to load the Thread package if it is needed.  If it is needed and not
+# loadable, the outcome depends on $http(-threadlevel):
+# value 0 => Thread package not required, no problem
+# value 1 => operate as if -threadlevel 0
+# value 2 => error return
+#
+# Arguments: none
+# Return Value: none
+# ------------------------------------------------------------------------------
+
+proc http::LoadThreadIfNeeded {} {
+    variable http
+    if {$http(usingThread) || ($http(-threadlevel) == 0)} {
+        return
+    }
+    if {[catch {package require Thread}]} {
+        if {$http(-threadlevel) == 2} {
+            set msg {[http::config -threadlevel] has value 2,\
+                     but the Thread package is not available}
+            return -code error $msg
+        }
+        return
+    }
+    set http(usingThread) 1
+    return
+}
+
+
+# ------------------------------------------------------------------------------
+#  Proc http::SockInThread
+# ------------------------------------------------------------------------------
+# Command http::socket is a ::socket replacement.  It defines and runs this
+# command, http::SockInThread, in a peer thread.
+#
+# Arguments:
+# caller
+# defcmd
+# sockargs
+#
+# Return value: list of values that describe the outcome.  The return is
+# intended to be a normal (non-error) return in all cases.
+# ------------------------------------------------------------------------------
+
+proc http::SockInThread {caller defcmd sockargs} {
+    package require Thread
+    
+    set catchCode [catch {eval $defcmd $sockargs} sock errdict]
+    if {$catchCode == 0} {
+        set catchCode [catch {thread::transfer $caller $sock; set sock} sock errdict]
+    }
+    return [list $catchCode $errdict $sock]
+}
+
+
+# ------------------------------------------------------------------------------
+#  Proc ::http::cwaiter::cwait
+# ------------------------------------------------------------------------------
+# Command to substitute for vwait, without the ordering issues.
+# A command that uses cwait must be a coroutine that is launched by an event,
+# e.g. fileevent or after idle, and has no calling code to be resumed upon
+# "yield".  It cannot return a value.
+#
+# Arguments:
+# varName      - fully-qualified name of the variable that the calling script
+#                will write to resume the coroutine.  Any scalar variable or
+#                array element is permitted.
+# coroName     - (optional) name of the coroutine to be called when varName is
+#                written - defaults to this coroutine
+# timeout      - (optional) timeout value in ms
+# timeoutValue - (optional) value to assign to varName if there is a timeout
+#
+# Return Value: none
+# ------------------------------------------------------------------------------
+
+namespace eval ::http::cwaiter {
+    namespace export cwait
+    variable log   {}
+    variable logOn 0
+}
+
+proc ::http::cwaiter::cwait {
+    varName {coroName {}} {timeout {}} {timeoutValue {}}
+} {
+    set thisCoro [info coroutine]
+    if {$thisCoro eq {}} {
+        return -code error {cwait cannot be called outside a coroutine}
+    }
+    if {$coroName eq {}} {
+        set coroName $thisCoro
+    }
+    if {[string range $varName 0 1] ne {::}} {
+        return -code error {argument varName must be fully qualified}
+    }
+    if {$timeout eq {}} {
+        set toe {}
+    } elseif {[string is integer -strict $timeout] && ($timeout > 0)} {
+        set toe [after $timeout [list set $varName $timeoutValue]]
+    } else {
+        return -code error {if timeout is supplied it must be a positive integer}
+    }
+
+    set cmd [list ::http::cwaiter::CwaitHelper $varName $coroName $toe]
+    trace add variable $varName write $cmd
+    CoLog "Yield $varName $coroName"
+    yield
+    CoLog "Resume $varName $coroName"
+    return
+}
+
+
+# ------------------------------------------------------------------------------
+#  Proc ::http::cwaiter::CwaitHelper
+# ------------------------------------------------------------------------------
+# Helper command called by the trace set by cwait.
+# - Ignores the arguments added by trace.
+# - A simple call to $coroName works, and in error cases gives a suitable stack
+#   trace, but because it is inside a trace the headline error message is
+#   something like {can't set "::Result(6)": error}, not the actual
+#   error.  So let the trace command return.
+# - Remove the trace immediately.  We don't want multiple calls.
+# ------------------------------------------------------------------------------
+
+proc ::http::cwaiter::CwaitHelper {varName coroName toe args} {
+    CoLog "got $varName for $coroName"
+    set cmd [list ::http::cwaiter::CwaitHelper $varName $coroName $toe]
+    trace remove variable $varName write $cmd
+    after cancel $toe
+
+    after 0 $coroName
+    return
+}
+
+
+# ------------------------------------------------------------------------------
+#  Proc ::http::cwaiter::LogInit
+# ------------------------------------------------------------------------------
+# Call this command to initiate debug logging and clear the log.
+# ------------------------------------------------------------------------------
+
+proc ::http::cwaiter::LogInit {} {
+    variable log
+    variable logOn
+    set log {}
+    set logOn 1
+    return
+}
+
+proc ::http::cwaiter::LogRead {} {
+    variable log
+    return $log
+}
+
+proc ::http::cwaiter::CoLog {msg} {
+    variable log
+    variable logOn
+    if {$logOn} {
+        append log $msg \n
+    }
+    return
+}
+
+namespace eval ::http {
+    namespace import ::http::cwaiter::*
 }
 
 # Local variables:
diff --git a/library/tzdata/America/Punta_Arenas b/library/tzdata/America/Punta_Arenas
index 959a0c1..8b06e6a 100644
--- a/library/tzdata/America/Punta_Arenas
+++ b/library/tzdata/America/Punta_Arenas
@@ -21,6 +21,7 @@ set TZData(:America/Punta_Arenas) {
     {-1178132400 -14400 0 -04}
     {-870552000 -18000 0 -05}
     {-865278000 -14400 0 -04}
+    {-736632000 -14400 1 -04}
     {-718056000 -18000 0 -05}
     {-713649600 -14400 0 -04}
     {-36619200 -10800 1 -04}
diff --git a/library/tzdata/America/Santiago b/library/tzdata/America/Santiago
index 801d3f2..13b8b99 100644
--- a/library/tzdata/America/Santiago
+++ b/library/tzdata/America/Santiago
@@ -22,7 +22,7 @@ set TZData(:America/Santiago) {
     {-870552000 -18000 0 -05}
     {-865278000 -14400 0 -04}
     {-740520000 -10800 1 -03}
-    {-736376400 -14400 0 -04}
+    {-736635600 -14400 1 -04}
     {-718056000 -18000 0 -05}
     {-713649600 -14400 0 -04}
     {-36619200 -10800 1 -04}
@@ -131,7 +131,7 @@ set TZData(:America/Santiago) {
     {1617505200 -14400 0 -04}
     {1630814400 -10800 1 -04}
     {1648954800 -14400 0 -04}
-    {1662264000 -10800 1 -04}
+    {1662868800 -10800 1 -04}
     {1680404400 -14400 0 -04}
     {1693713600 -10800 1 -04}
     {1712458800 -14400 0 -04}
diff --git a/library/tzdata/Antarctica/Vostok b/library/tzdata/Antarctica/Vostok
index 7f345a2..1a19a5d 100644
--- a/library/tzdata/Antarctica/Vostok
+++ b/library/tzdata/Antarctica/Vostok
@@ -1,6 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Antarctica/Vostok) {
-    {-9223372036854775808 0 0 -00}
-    {-380073600 21600 0 +06}
+if {![info exists TZData(Asia/Urumqi)]} {
+    LoadTimeZoneFile Asia/Urumqi
 }
+set TZData(:Antarctica/Vostok) $TZData(:Asia/Urumqi)
diff --git a/library/tzdata/Arctic/Longyearbyen b/library/tzdata/Arctic/Longyearbyen
index 51f83dc..4b52387 100644
--- a/library/tzdata/Arctic/Longyearbyen
+++ b/library/tzdata/Arctic/Longyearbyen
@@ -1,5 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-if {![info exists TZData(Europe/Oslo)]} {
-    LoadTimeZoneFile Europe/Oslo
+if {![info exists TZData(Europe/Berlin)]} {
+    LoadTimeZoneFile Europe/Berlin
 }
-set TZData(:Arctic/Longyearbyen) $TZData(:Europe/Oslo)
+set TZData(:Arctic/Longyearbyen) $TZData(:Europe/Berlin)
diff --git a/library/tzdata/Asia/Brunei b/library/tzdata/Asia/Brunei
index e8cc8c3..ec1a78d 100644
--- a/library/tzdata/Asia/Brunei
+++ b/library/tzdata/Asia/Brunei
@@ -1,7 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Asia/Brunei) {
-    {-9223372036854775808 27580 0 LMT}
-    {-1383464380 27000 0 +0730}
-    {-1167636600 28800 0 +08}
+if {![info exists TZData(Asia/Kuching)]} {
+    LoadTimeZoneFile Asia/Kuching
 }
+set TZData(:Asia/Brunei) $TZData(:Asia/Kuching)
diff --git a/library/tzdata/Asia/Ho_Chi_Minh b/library/tzdata/Asia/Ho_Chi_Minh
index b4e749b..4689516 100644
--- a/library/tzdata/Asia/Ho_Chi_Minh
+++ b/library/tzdata/Asia/Ho_Chi_Minh
@@ -1,8 +1,8 @@
 # created by tools/tclZIC.tcl - do not edit
 
 set TZData(:Asia/Ho_Chi_Minh) {
-    {-9223372036854775808 25600 0 LMT}
-    {-2004073600 25590 0 PLMT}
+    {-9223372036854775808 25590 0 LMT}
+    {-2004073590 25590 0 PLMT}
     {-1851577590 25200 0 +07}
     {-852105600 28800 0 +08}
     {-782643600 32400 0 +09}
diff --git a/library/tzdata/Asia/Kuala_Lumpur b/library/tzdata/Asia/Kuala_Lumpur
index 84eae1d..177539a 100644
--- a/library/tzdata/Asia/Kuala_Lumpur
+++ b/library/tzdata/Asia/Kuala_Lumpur
@@ -1,13 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Asia/Kuala_Lumpur) {
-    {-9223372036854775808 24406 0 LMT}
-    {-2177477206 24925 0 SMT}
-    {-2038200925 25200 0 +07}
-    {-1167634800 26400 1 +0720}
-    {-1073028000 26400 0 +0720}
-    {-894180000 27000 0 +0730}
-    {-879665400 32400 0 +09}
-    {-767005200 27000 0 +0730}
-    {378664200 28800 0 +08}
+if {![info exists TZData(Asia/Singapore)]} {
+    LoadTimeZoneFile Asia/Singapore
 }
+set TZData(:Asia/Kuala_Lumpur) $TZData(:Asia/Singapore)
diff --git a/library/tzdata/Asia/Tehran b/library/tzdata/Asia/Tehran
index 4515523..c453c48 100644
--- a/library/tzdata/Asia/Tehran
+++ b/library/tzdata/Asia/Tehran
@@ -3,12 +3,13 @@
 set TZData(:Asia/Tehran) {
     {-9223372036854775808 12344 0 LMT}
     {-1704165944 12344 0 TMT}
-    {-757394744 12600 0 +0330}
-    {247177800 14400 0 +04}
-    {259272000 18000 1 +04}
-    {277758000 14400 0 +04}
+    {-1090466744 12600 0 +0330}
+    {227820600 16200 1 +0330}
+    {246227400 14400 0 +04}
+    {259617600 18000 1 +04}
+    {271108800 14400 0 +04}
     {283982400 12600 0 +0330}
-    {290809800 16200 1 +0330}
+    {296598600 16200 1 +0330}
     {306531000 12600 0 +0330}
     {322432200 16200 1 +0330}
     {338499000 12600 0 +0330}
@@ -72,158 +73,4 @@ set TZData(:Asia/Tehran) {
     {1632252600 12600 0 +0330}
     {1647894600 16200 1 +0330}
     {1663788600 12600 0 +0330}
-    {1679430600 16200 1 +0330}
-    {1695324600 12600 0 +0330}
-    {1710966600 16200 1 +0330}
-    {1726860600 12600 0 +0330}
-    {1742589000 16200 1 +0330}
-    {1758483000 12600 0 +0330}
-    {1774125000 16200 1 +0330}
-    {1790019000 12600 0 +0330}
-    {1805661000 16200 1 +0330}
-    {1821555000 12600 0 +0330}
-    {1837197000 16200 1 +0330}
-    {1853091000 12600 0 +0330}
-    {1868733000 16200 1 +0330}
-    {1884627000 12600 0 +0330}
-    {1900355400 16200 1 +0330}
-    {1916249400 12600 0 +0330}
-    {1931891400 16200 1 +0330}
-    {1947785400 12600 0 +0330}
-    {1963427400 16200 1 +0330}
-    {1979321400 12600 0 +0330}
-    {1994963400 16200 1 +0330}
-    {2010857400 12600 0 +0330}
-    {2026585800 16200 1 +0330}
-    {2042479800 12600 0 +0330}
-    {2058121800 16200 1 +0330}
-    {2074015800 12600 0 +0330}
-    {2089657800 16200 1 +0330}
-    {2105551800 12600 0 +0330}
-    {2121193800 16200 1 +0330}
-    {2137087800 12600 0 +0330}
-    {2152816200 16200 1 +0330}
-    {2168710200 12600 0 +0330}
-    {2184352200 16200 1 +0330}
-    {2200246200 12600 0 +0330}
-    {2215888200 16200 1 +0330}
-    {2231782200 12600 0 +0330}
-    {2247424200 16200 1 +0330}
-    {2263318200 12600 0 +0330}
-    {2279046600 16200 1 +0330}
-    {2294940600 12600 0 +0330}
-    {2310582600 16200 1 +0330}
-    {2326476600 12600 0 +0330}
-    {2342118600 16200 1 +0330}
-    {2358012600 12600 0 +0330}
-    {2373654600 16200 1 +0330}
-    {2389548600 12600 0 +0330}
-    {2405277000 16200 1 +0330}
-    {2421171000 12600 0 +0330}
-    {2436813000 16200 1 +0330}
-    {2452707000 12600 0 +0330}
-    {2468349000 16200 1 +0330}
-    {2484243000 12600 0 +0330}
-    {2499885000 16200 1 +0330}
-    {2515779000 12600 0 +0330}
-    {2531507400 16200 1 +0330}
-    {2547401400 12600 0 +0330}
-    {2563043400 16200 1 +0330}
-    {2578937400 12600 0 +0330}
-    {2594579400 16200 1 +0330}
-    {2610473400 12600 0 +0330}
-    {2626115400 16200 1 +0330}
-    {2642009400 12600 0 +0330}
-    {2657737800 16200 1 +0330}
-    {2673631800 12600 0 +0330}
-    {2689273800 16200 1 +0330}
-    {2705167800 12600 0 +0330}
-    {2720809800 16200 1 +0330}
-    {2736703800 12600 0 +0330}
-    {2752345800 16200 1 +0330}
-    {2768239800 12600 0 +0330}
-    {2783968200 16200 1 +0330}
-    {2799862200 12600 0 +0330}
-    {2815504200 16200 1 +0330}
-    {2831398200 12600 0 +0330}
-    {2847040200 16200 1 +0330}
-    {2862934200 12600 0 +0330}
-    {2878576200 16200 1 +0330}
-    {2894470200 12600 0 +0330}
-    {2910112200 16200 1 +0330}
-    {2926006200 12600 0 +0330}
-    {2941734600 16200 1 +0330}
-    {2957628600 12600 0 +0330}
-    {2973270600 16200 1 +0330}
-    {2989164600 12600 0 +0330}
-    {3004806600 16200 1 +0330}
-    {3020700600 12600 0 +0330}
-    {3036342600 16200 1 +0330}
-    {3052236600 12600 0 +0330}
-    {3067965000 16200 1 +0330}
-    {3083859000 12600 0 +0330}
-    {3099501000 16200 1 +0330}
-    {3115395000 12600 0 +0330}
-    {3131037000 16200 1 +0330}
-    {3146931000 12600 0 +0330}
-    {3162573000 16200 1 +0330}
-    {3178467000 12600 0 +0330}
-    {3194195400 16200 1 +0330}
-    {3210089400 12600 0 +0330}
-    {3225731400 16200 1 +0330}
-    {3241625400 12600 0 +0330}
-    {3257267400 16200 1 +0330}
-    {3273161400 12600 0 +0330}
-    {3288803400 16200 1 +0330}
-    {3304697400 12600 0 +0330}
-    {3320425800 16200 1 +0330}
-    {3336319800 12600 0 +0330}
-    {3351961800 16200 1 +0330}
-    {3367855800 12600 0 +0330}
-    {3383497800 16200 1 +0330}
-    {3399391800 12600 0 +0330}
-    {3415033800 16200 1 +0330}
-    {3430927800 12600 0 +0330}
-    {3446656200 16200 1 +0330}
-    {3462550200 12600 0 +0330}
-    {3478192200 16200 1 +0330}
-    {3494086200 12600 0 +0330}
-    {3509728200 16200 1 +0330}
-    {3525622200 12600 0 +0330}
-    {3541264200 16200 1 +0330}
-    {3557158200 12600 0 +0330}
-    {3572886600 16200 1 +0330}
-    {3588780600 12600 0 +0330}
-    {3604422600 16200 1 +0330}
-    {3620316600 12600 0 +0330}
-    {3635958600 16200 1 +0330}
-    {3651852600 12600 0 +0330}
-    {3667494600 16200 1 +0330}
-    {3683388600 12600 0 +0330}
-    {3699117000 16200 1 +0330}
-    {3715011000 12600 0 +0330}
-    {3730653000 16200 1 +0330}
-    {3746547000 12600 0 +0330}
-    {3762189000 16200 1 +0330}
-    {3778083000 12600 0 +0330}
-    {3793725000 16200 1 +0330}
-    {3809619000 12600 0 +0330}
-    {3825261000 16200 1 +0330}
-    {3841155000 12600 0 +0330}
-    {3856883400 16200 1 +0330}
-    {3872777400 12600 0 +0330}
-    {3888419400 16200 1 +0330}
-    {3904313400 12600 0 +0330}
-    {3919955400 16200 1 +0330}
-    {3935849400 12600 0 +0330}
-    {3951491400 16200 1 +0330}
-    {3967385400 12600 0 +0330}
-    {3983113800 16200 1 +0330}
-    {3999007800 12600 0 +0330}
-    {4014649800 16200 1 +0330}
-    {4030543800 12600 0 +0330}
-    {4046185800 16200 1 +0330}
-    {4062079800 12600 0 +0330}
-    {4077721800 16200 1 +0330}
-    {4093615800 12600 0 +0330}
 }
diff --git a/library/tzdata/Atlantic/Jan_Mayen b/library/tzdata/Atlantic/Jan_Mayen
index e592187..468d819 100644
--- a/library/tzdata/Atlantic/Jan_Mayen
+++ b/library/tzdata/Atlantic/Jan_Mayen
@@ -1,5 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-if {![info exists TZData(Europe/Oslo)]} {
-    LoadTimeZoneFile Europe/Oslo
+if {![info exists TZData(Europe/Berlin)]} {
+    LoadTimeZoneFile Europe/Berlin
 }
-set TZData(:Atlantic/Jan_Mayen) $TZData(:Europe/Oslo)
+set TZData(:Atlantic/Jan_Mayen) $TZData(:Europe/Berlin)
diff --git a/library/tzdata/Atlantic/Reykjavik b/library/tzdata/Atlantic/Reykjavik
index 6270572..3c4a133 100644
--- a/library/tzdata/Atlantic/Reykjavik
+++ b/library/tzdata/Atlantic/Reykjavik
@@ -1,73 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Atlantic/Reykjavik) {
-    {-9223372036854775808 -5280 0 LMT}
-    {-1956609120 -3600 0 -01}
-    {-1668211200 0 1 -01}
-    {-1647212400 -3600 0 -01}
-    {-1636675200 0 1 -01}
-    {-1613430000 -3600 0 -01}
-    {-1605139200 0 1 -01}
-    {-1581894000 -3600 0 -01}
-    {-1539561600 0 1 -01}
-    {-1531350000 -3600 0 -01}
-    {-968025600 0 1 -01}
-    {-952293600 -3600 0 -01}
-    {-942008400 0 1 -01}
-    {-920239200 -3600 0 -01}
-    {-909957600 0 1 -01}
-    {-888789600 -3600 0 -01}
-    {-877903200 0 1 -01}
-    {-857944800 -3600 0 -01}
-    {-846453600 0 1 -01}
-    {-826495200 -3600 0 -01}
-    {-815004000 0 1 -01}
-    {-795045600 -3600 0 -01}
-    {-783554400 0 1 -01}
-    {-762991200 -3600 0 -01}
-    {-752104800 0 1 -01}
-    {-731541600 -3600 0 -01}
-    {-717631200 0 1 -01}
-    {-700092000 -3600 0 -01}
-    {-686181600 0 1 -01}
-    {-668642400 -3600 0 -01}
-    {-654732000 0 1 -01}
-    {-636588000 -3600 0 -01}
-    {-623282400 0 1 -01}
-    {-605743200 -3600 0 -01}
-    {-591832800 0 1 -01}
-    {-573688800 -3600 0 -01}
-    {-559778400 0 1 -01}
-    {-542239200 -3600 0 -01}
-    {-528328800 0 1 -01}
-    {-510789600 -3600 0 -01}
-    {-496879200 0 1 -01}
-    {-479340000 -3600 0 -01}
-    {-465429600 0 1 -01}
-    {-447890400 -3600 0 -01}
-    {-433980000 0 1 -01}
-    {-415836000 -3600 0 -01}
-    {-401925600 0 1 -01}
-    {-384386400 -3600 0 -01}
-    {-370476000 0 1 -01}
-    {-352936800 -3600 0 -01}
-    {-339026400 0 1 -01}
-    {-321487200 -3600 0 -01}
-    {-307576800 0 1 -01}
-    {-290037600 -3600 0 -01}
-    {-276127200 0 1 -01}
-    {-258588000 -3600 0 -01}
-    {-244677600 0 1 -01}
-    {-226533600 -3600 0 -01}
-    {-212623200 0 1 -01}
-    {-195084000 -3600 0 -01}
-    {-181173600 0 1 -01}
-    {-163634400 -3600 0 -01}
-    {-149724000 0 1 -01}
-    {-132184800 -3600 0 -01}
-    {-118274400 0 1 -01}
-    {-100735200 -3600 0 -01}
-    {-86824800 0 1 -01}
-    {-68680800 -3600 0 -01}
-    {-54770400 0 0 GMT}
+if {![info exists TZData(Africa/Abidjan)]} {
+    LoadTimeZoneFile Africa/Abidjan
 }
+set TZData(:Atlantic/Reykjavik) $TZData(:Africa/Abidjan)
diff --git a/library/tzdata/Canada/East-Saskatchewan b/library/tzdata/Canada/East-Saskatchewan
deleted file mode 100644
index f7e500c..0000000
--- a/library/tzdata/Canada/East-Saskatchewan
+++ /dev/null
@@ -1,5 +0,0 @@
-# created by tools/tclZIC.tcl - do not edit
-if {![info exists TZData(America/Regina)]} {
-    LoadTimeZoneFile America/Regina
-}
-set TZData(:Canada/East-Saskatchewan) $TZData(:America/Regina)
diff --git a/library/tzdata/Europe/Amsterdam b/library/tzdata/Europe/Amsterdam
index b683c99..7fbe3aa 100644
--- a/library/tzdata/Europe/Amsterdam
+++ b/library/tzdata/Europe/Amsterdam
@@ -1,310 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Europe/Amsterdam) {
-    {-9223372036854775808 1172 0 LMT}
-    {-4260212372 1172 0 AMT}
-    {-1693700372 4772 1 NST}
-    {-1680484772 1172 0 AMT}
-    {-1663453172 4772 1 NST}
-    {-1650147572 1172 0 AMT}
-    {-1633213172 4772 1 NST}
-    {-1617488372 1172 0 AMT}
-    {-1601158772 4772 1 NST}
-    {-1586038772 1172 0 AMT}
-    {-1569709172 4772 1 NST}
-    {-1554589172 1172 0 AMT}
-    {-1538259572 4772 1 NST}
-    {-1523139572 1172 0 AMT}
-    {-1507501172 4772 1 NST}
-    {-1490566772 1172 0 AMT}
-    {-1470176372 4772 1 NST}
-    {-1459117172 1172 0 AMT}
-    {-1443997172 4772 1 NST}
-    {-1427667572 1172 0 AMT}
-    {-1406672372 4772 1 NST}
-    {-1396217972 1172 0 AMT}
-    {-1376950772 4772 1 NST}
-    {-1364768372 1172 0 AMT}
-    {-1345414772 4772 1 NST}
-    {-1333318772 1172 0 AMT}
-    {-1313792372 4772 1 NST}
-    {-1301264372 1172 0 AMT}
-    {-1282256372 4772 1 NST}
-    {-1269814772 1172 0 AMT}
-    {-1250720372 4772 1 NST}
-    {-1238365172 1172 0 AMT}
-    {-1219184372 4772 1 NST}
-    {-1206915572 1172 0 AMT}
-    {-1186957172 4772 1 NST}
-    {-1175465972 1172 0 AMT}
-    {-1156025972 4772 1 NST}
-    {-1143411572 1172 0 AMT}
-    {-1124489972 4772 1 NST}
-    {-1111961972 1172 0 AMT}
-    {-1092953972 4772 1 NST}
-    {-1080512372 1172 0 AMT}
-    {-1061331572 4772 1 NST}
-    {-1049062772 1172 0 AMT}
-    {-1029190772 4772 1 NST}
-    {-1025741972 4800 0 +0120}
-    {-1017613200 1200 0 +0020}
-    {-998259600 4800 1 +0120}
-    {-986163600 1200 0 +0020}
-    {-966723600 4800 1 +0120}
-    {-954109200 1200 0 +0020}
-    {-935022000 7200 0 CEST}
-    {-857257200 3600 0 CET}
-    {-844556400 7200 1 CEST}
-    {-828226800 3600 0 CET}
-    {-812502000 7200 1 CEST}
-    {-796777200 3600 0 CET}
-    {-781052400 7200 0 CEST}
-    {-766623600 3600 0 CET}
-    {220921200 3600 0 CET}
-    {228877200 7200 1 CEST}
-    {243997200 3600 0 CET}
-    {260326800 7200 1 CEST}
-    {276051600 3600 0 CET}
-    {291776400 7200 1 CEST}
-    {307501200 3600 0 CET}
-    {323830800 7200 1 CEST}
-    {338950800 3600 0 CET}
-    {354675600 7200 1 CEST}
-    {370400400 3600 0 CET}
-    {386125200 7200 1 CEST}
-    {401850000 3600 0 CET}
-    {417574800 7200 1 CEST}
-    {433299600 3600 0 CET}
-    {449024400 7200 1 CEST}
-    {465354000 3600 0 CET}
-    {481078800 7200 1 CEST}
-    {496803600 3600 0 CET}
-    {512528400 7200 1 CEST}
-    {528253200 3600 0 CET}
-    {543978000 7200 1 CEST}
-    {559702800 3600 0 CET}
-    {575427600 7200 1 CEST}
-    {591152400 3600 0 CET}
-    {606877200 7200 1 CEST}
-    {622602000 3600 0 CET}
-    {638326800 7200 1 CEST}
-    {654656400 3600 0 CET}
-    {670381200 7200 1 CEST}
-    {686106000 3600 0 CET}
-    {701830800 7200 1 CEST}
-    {717555600 3600 0 CET}
-    {733280400 7200 1 CEST}
-    {749005200 3600 0 CET}
-    {764730000 7200 1 CEST}
-    {780454800 3600 0 CET}
-    {796179600 7200 1 CEST}
-    {811904400 3600 0 CET}
-    {828234000 7200 1 CEST}
-    {846378000 3600 0 CET}
-    {859683600 7200 1 CEST}
-    {877827600 3600 0 CET}
-    {891133200 7200 1 CEST}
-    {909277200 3600 0 CET}
-    {922582800 7200 1 CEST}
-    {941331600 3600 0 CET}
-    {954032400 7200 1 CEST}
-    {972781200 3600 0 CET}
-    {985482000 7200 1 CEST}
-    {1004230800 3600 0 CET}
-    {1017536400 7200 1 CEST}
-    {1035680400 3600 0 CET}
-    {1048986000 7200 1 CEST}
-    {1067130000 3600 0 CET}
-    {1080435600 7200 1 CEST}
-    {1099184400 3600 0 CET}
-    {1111885200 7200 1 CEST}
-    {1130634000 3600 0 CET}
-    {1143334800 7200 1 CEST}
-    {1162083600 3600 0 CET}
-    {1174784400 7200 1 CEST}
-    {1193533200 3600 0 CET}
-    {1206838800 7200 1 CEST}
-    {1224982800 3600 0 CET}
-    {1238288400 7200 1 CEST}
-    {1256432400 3600 0 CET}
-    {1269738000 7200 1 CEST}
-    {1288486800 3600 0 CET}
-    {1301187600 7200 1 CEST}
-    {1319936400 3600 0 CET}
-    {1332637200 7200 1 CEST}
-    {1351386000 3600 0 CET}
-    {1364691600 7200 1 CEST}
-    {1382835600 3600 0 CET}
-    {1396141200 7200 1 CEST}
-    {1414285200 3600 0 CET}
-    {1427590800 7200 1 CEST}
-    {1445734800 3600 0 CET}
-    {1459040400 7200 1 CEST}
-    {1477789200 3600 0 CET}
-    {1490490000 7200 1 CEST}
-    {1509238800 3600 0 CET}
-    {1521939600 7200 1 CEST}
-    {1540688400 3600 0 CET}
-    {1553994000 7200 1 CEST}
-    {1572138000 3600 0 CET}
-    {1585443600 7200 1 CEST}
-    {1603587600 3600 0 CET}
-    {1616893200 7200 1 CEST}
-    {1635642000 3600 0 CET}
-    {1648342800 7200 1 CEST}
-    {1667091600 3600 0 CET}
-    {1679792400 7200 1 CEST}
-    {1698541200 3600 0 CET}
-    {1711846800 7200 1 CEST}
-    {1729990800 3600 0 CET}
-    {1743296400 7200 1 CEST}
-    {1761440400 3600 0 CET}
-    {1774746000 7200 1 CEST}
-    {1792890000 3600 0 CET}
-    {1806195600 7200 1 CEST}
-    {1824944400 3600 0 CET}
-    {1837645200 7200 1 CEST}
-    {1856394000 3600 0 CET}
-    {1869094800 7200 1 CEST}
-    {1887843600 3600 0 CET}
-    {1901149200 7200 1 CEST}
-    {1919293200 3600 0 CET}
-    {1932598800 7200 1 CEST}
-    {1950742800 3600 0 CET}
-    {1964048400 7200 1 CEST}
-    {1982797200 3600 0 CET}
-    {1995498000 7200 1 CEST}
-    {2014246800 3600 0 CET}
-    {2026947600 7200 1 CEST}
-    {2045696400 3600 0 CET}
-    {2058397200 7200 1 CEST}
-    {2077146000 3600 0 CET}
-    {2090451600 7200 1 CEST}
-    {2108595600 3600 0 CET}
-    {2121901200 7200 1 CEST}
-    {2140045200 3600 0 CET}
-    {2153350800 7200 1 CEST}
-    {2172099600 3600 0 CET}
-    {2184800400 7200 1 CEST}
-    {2203549200 3600 0 CET}
-    {2216250000 7200 1 CEST}
-    {2234998800 3600 0 CET}
-    {2248304400 7200 1 CEST}
-    {2266448400 3600 0 CET}
-    {2279754000 7200 1 CEST}
-    {2297898000 3600 0 CET}
-    {2311203600 7200 1 CEST}
-    {2329347600 3600 0 CET}
-    {2342653200 7200 1 CEST}
-    {2361402000 3600 0 CET}
-    {2374102800 7200 1 CEST}
-    {2392851600 3600 0 CET}
-    {2405552400 7200 1 CEST}
-    {2424301200 3600 0 CET}
-    {2437606800 7200 1 CEST}
-    {2455750800 3600 0 CET}
-    {2469056400 7200 1 CEST}
-    {2487200400 3600 0 CET}
-    {2500506000 7200 1 CEST}
-    {2519254800 3600 0 CET}
-    {2531955600 7200 1 CEST}
-    {2550704400 3600 0 CET}
-    {2563405200 7200 1 CEST}
-    {2582154000 3600 0 CET}
-    {2595459600 7200 1 CEST}
-    {2613603600 3600 0 CET}
-    {2626909200 7200 1 CEST}
-    {2645053200 3600 0 CET}
-    {2658358800 7200 1 CEST}
-    {2676502800 3600 0 CET}
-    {2689808400 7200 1 CEST}
-    {2708557200 3600 0 CET}
-    {2721258000 7200 1 CEST}
-    {2740006800 3600 0 CET}
-    {2752707600 7200 1 CEST}
-    {2771456400 3600 0 CET}
-    {2784762000 7200 1 CEST}
-    {2802906000 3600 0 CET}
-    {2816211600 7200 1 CEST}
-    {2834355600 3600 0 CET}
-    {2847661200 7200 1 CEST}
-    {2866410000 3600 0 CET}
-    {2879110800 7200 1 CEST}
-    {2897859600 3600 0 CET}
-    {2910560400 7200 1 CEST}
-    {2929309200 3600 0 CET}
-    {2942010000 7200 1 CEST}
-    {2960758800 3600 0 CET}
-    {2974064400 7200 1 CEST}
-    {2992208400 3600 0 CET}
-    {3005514000 7200 1 CEST}
-    {3023658000 3600 0 CET}
-    {3036963600 7200 1 CEST}
-    {3055712400 3600 0 CET}
-    {3068413200 7200 1 CEST}
-    {3087162000 3600 0 CET}
-    {3099862800 7200 1 CEST}
-    {3118611600 3600 0 CET}
-    {3131917200 7200 1 CEST}
-    {3150061200 3600 0 CET}
-    {3163366800 7200 1 CEST}
-    {3181510800 3600 0 CET}
-    {3194816400 7200 1 CEST}
-    {3212960400 3600 0 CET}
-    {3226266000 7200 1 CEST}
-    {3245014800 3600 0 CET}
-    {3257715600 7200 1 CEST}
-    {3276464400 3600 0 CET}
-    {3289165200 7200 1 CEST}
-    {3307914000 3600 0 CET}
-    {3321219600 7200 1 CEST}
-    {3339363600 3600 0 CET}
-    {3352669200 7200 1 CEST}
-    {3370813200 3600 0 CET}
-    {3384118800 7200 1 CEST}
-    {3402867600 3600 0 CET}
-    {3415568400 7200 1 CEST}
-    {3434317200 3600 0 CET}
-    {3447018000 7200 1 CEST}
-    {3465766800 3600 0 CET}
-    {3479072400 7200 1 CEST}
-    {3497216400 3600 0 CET}
-    {3510522000 7200 1 CEST}
-    {3528666000 3600 0 CET}
-    {3541971600 7200 1 CEST}
-    {3560115600 3600 0 CET}
-    {3573421200 7200 1 CEST}
-    {3592170000 3600 0 CET}
-    {3604870800 7200 1 CEST}
-    {3623619600 3600 0 CET}
-    {3636320400 7200 1 CEST}
-    {3655069200 3600 0 CET}
-    {3668374800 7200 1 CEST}
-    {3686518800 3600 0 CET}
-    {3699824400 7200 1 CEST}
-    {3717968400 3600 0 CET}
-    {3731274000 7200 1 CEST}
-    {3750022800 3600 0 CET}
-    {3762723600 7200 1 CEST}
-    {3781472400 3600 0 CET}
-    {3794173200 7200 1 CEST}
-    {3812922000 3600 0 CET}
-    {3825622800 7200 1 CEST}
-    {3844371600 3600 0 CET}
-    {3857677200 7200 1 CEST}
-    {3875821200 3600 0 CET}
-    {3889126800 7200 1 CEST}
-    {3907270800 3600 0 CET}
-    {3920576400 7200 1 CEST}
-    {3939325200 3600 0 CET}
-    {3952026000 7200 1 CEST}
-    {3970774800 3600 0 CET}
-    {3983475600 7200 1 CEST}
-    {4002224400 3600 0 CET}
-    {4015530000 7200 1 CEST}
-    {4033674000 3600 0 CET}
-    {4046979600 7200 1 CEST}
-    {4065123600 3600 0 CET}
-    {4078429200 7200 1 CEST}
-    {4096573200 3600 0 CET}
+if {![info exists TZData(Europe/Brussels)]} {
+    LoadTimeZoneFile Europe/Brussels
 }
+set TZData(:Europe/Amsterdam) $TZData(:Europe/Brussels)
diff --git a/library/tzdata/Europe/Copenhagen b/library/tzdata/Europe/Copenhagen
index c747e58..1b144d1 100644
--- a/library/tzdata/Europe/Copenhagen
+++ b/library/tzdata/Europe/Copenhagen
@@ -1,264 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Europe/Copenhagen) {
-    {-9223372036854775808 3020 0 LMT}
-    {-2524524620 3020 0 CMT}
-    {-2398294220 3600 0 CET}
-    {-1692496800 7200 1 CEST}
-    {-1680490800 3600 0 CET}
-    {-935110800 7200 1 CEST}
-    {-857257200 3600 0 CET}
-    {-844556400 7200 1 CEST}
-    {-828226800 3600 0 CET}
-    {-812502000 7200 1 CEST}
-    {-796777200 3600 0 CET}
-    {-781052400 7200 0 CEST}
-    {-769388400 3600 0 CET}
-    {-747010800 7200 1 CEST}
-    {-736383600 3600 0 CET}
-    {-715215600 7200 1 CEST}
-    {-706748400 3600 0 CET}
-    {-683161200 7200 1 CEST}
-    {-675298800 3600 0 CET}
-    {315529200 3600 0 CET}
-    {323830800 7200 1 CEST}
-    {338950800 3600 0 CET}
-    {354675600 7200 1 CEST}
-    {370400400 3600 0 CET}
-    {386125200 7200 1 CEST}
-    {401850000 3600 0 CET}
-    {417574800 7200 1 CEST}
-    {433299600 3600 0 CET}
-    {449024400 7200 1 CEST}
-    {465354000 3600 0 CET}
-    {481078800 7200 1 CEST}
-    {496803600 3600 0 CET}
-    {512528400 7200 1 CEST}
-    {528253200 3600 0 CET}
-    {543978000 7200 1 CEST}
-    {559702800 3600 0 CET}
-    {575427600 7200 1 CEST}
-    {591152400 3600 0 CET}
-    {606877200 7200 1 CEST}
-    {622602000 3600 0 CET}
-    {638326800 7200 1 CEST}
-    {654656400 3600 0 CET}
-    {670381200 7200 1 CEST}
-    {686106000 3600 0 CET}
-    {701830800 7200 1 CEST}
-    {717555600 3600 0 CET}
-    {733280400 7200 1 CEST}
-    {749005200 3600 0 CET}
-    {764730000 7200 1 CEST}
-    {780454800 3600 0 CET}
-    {796179600 7200 1 CEST}
-    {811904400 3600 0 CET}
-    {828234000 7200 1 CEST}
-    {846378000 3600 0 CET}
-    {859683600 7200 1 CEST}
-    {877827600 3600 0 CET}
-    {891133200 7200 1 CEST}
-    {909277200 3600 0 CET}
-    {922582800 7200 1 CEST}
-    {941331600 3600 0 CET}
-    {954032400 7200 1 CEST}
-    {972781200 3600 0 CET}
-    {985482000 7200 1 CEST}
-    {1004230800 3600 0 CET}
-    {1017536400 7200 1 CEST}
-    {1035680400 3600 0 CET}
-    {1048986000 7200 1 CEST}
-    {1067130000 3600 0 CET}
-    {1080435600 7200 1 CEST}
-    {1099184400 3600 0 CET}
-    {1111885200 7200 1 CEST}
-    {1130634000 3600 0 CET}
-    {1143334800 7200 1 CEST}
-    {1162083600 3600 0 CET}
-    {1174784400 7200 1 CEST}
-    {1193533200 3600 0 CET}
-    {1206838800 7200 1 CEST}
-    {1224982800 3600 0 CET}
-    {1238288400 7200 1 CEST}
-    {1256432400 3600 0 CET}
-    {1269738000 7200 1 CEST}
-    {1288486800 3600 0 CET}
-    {1301187600 7200 1 CEST}
-    {1319936400 3600 0 CET}
-    {1332637200 7200 1 CEST}
-    {1351386000 3600 0 CET}
-    {1364691600 7200 1 CEST}
-    {1382835600 3600 0 CET}
-    {1396141200 7200 1 CEST}
-    {1414285200 3600 0 CET}
-    {1427590800 7200 1 CEST}
-    {1445734800 3600 0 CET}
-    {1459040400 7200 1 CEST}
-    {1477789200 3600 0 CET}
-    {1490490000 7200 1 CEST}
-    {1509238800 3600 0 CET}
-    {1521939600 7200 1 CEST}
-    {1540688400 3600 0 CET}
-    {1553994000 7200 1 CEST}
-    {1572138000 3600 0 CET}
-    {1585443600 7200 1 CEST}
-    {1603587600 3600 0 CET}
-    {1616893200 7200 1 CEST}
-    {1635642000 3600 0 CET}
-    {1648342800 7200 1 CEST}
-    {1667091600 3600 0 CET}
-    {1679792400 7200 1 CEST}
-    {1698541200 3600 0 CET}
-    {1711846800 7200 1 CEST}
-    {1729990800 3600 0 CET}
-    {1743296400 7200 1 CEST}
-    {1761440400 3600 0 CET}
-    {1774746000 7200 1 CEST}
-    {1792890000 3600 0 CET}
-    {1806195600 7200 1 CEST}
-    {1824944400 3600 0 CET}
-    {1837645200 7200 1 CEST}
-    {1856394000 3600 0 CET}
-    {1869094800 7200 1 CEST}
-    {1887843600 3600 0 CET}
-    {1901149200 7200 1 CEST}
-    {1919293200 3600 0 CET}
-    {1932598800 7200 1 CEST}
-    {1950742800 3600 0 CET}
-    {1964048400 7200 1 CEST}
-    {1982797200 3600 0 CET}
-    {1995498000 7200 1 CEST}
-    {2014246800 3600 0 CET}
-    {2026947600 7200 1 CEST}
-    {2045696400 3600 0 CET}
-    {2058397200 7200 1 CEST}
-    {2077146000 3600 0 CET}
-    {2090451600 7200 1 CEST}
-    {2108595600 3600 0 CET}
-    {2121901200 7200 1 CEST}
-    {2140045200 3600 0 CET}
-    {2153350800 7200 1 CEST}
-    {2172099600 3600 0 CET}
-    {2184800400 7200 1 CEST}
-    {2203549200 3600 0 CET}
-    {2216250000 7200 1 CEST}
-    {2234998800 3600 0 CET}
-    {2248304400 7200 1 CEST}
-    {2266448400 3600 0 CET}
-    {2279754000 7200 1 CEST}
-    {2297898000 3600 0 CET}
-    {2311203600 7200 1 CEST}
-    {2329347600 3600 0 CET}
-    {2342653200 7200 1 CEST}
-    {2361402000 3600 0 CET}
-    {2374102800 7200 1 CEST}
-    {2392851600 3600 0 CET}
-    {2405552400 7200 1 CEST}
-    {2424301200 3600 0 CET}
-    {2437606800 7200 1 CEST}
-    {2455750800 3600 0 CET}
-    {2469056400 7200 1 CEST}
-    {2487200400 3600 0 CET}
-    {2500506000 7200 1 CEST}
-    {2519254800 3600 0 CET}
-    {2531955600 7200 1 CEST}
-    {2550704400 3600 0 CET}
-    {2563405200 7200 1 CEST}
-    {2582154000 3600 0 CET}
-    {2595459600 7200 1 CEST}
-    {2613603600 3600 0 CET}
-    {2626909200 7200 1 CEST}
-    {2645053200 3600 0 CET}
-    {2658358800 7200 1 CEST}
-    {2676502800 3600 0 CET}
-    {2689808400 7200 1 CEST}
-    {2708557200 3600 0 CET}
-    {2721258000 7200 1 CEST}
-    {2740006800 3600 0 CET}
-    {2752707600 7200 1 CEST}
-    {2771456400 3600 0 CET}
-    {2784762000 7200 1 CEST}
-    {2802906000 3600 0 CET}
-    {2816211600 7200 1 CEST}
-    {2834355600 3600 0 CET}
-    {2847661200 7200 1 CEST}
-    {2866410000 3600 0 CET}
-    {2879110800 7200 1 CEST}
-    {2897859600 3600 0 CET}
-    {2910560400 7200 1 CEST}
-    {2929309200 3600 0 CET}
-    {2942010000 7200 1 CEST}
-    {2960758800 3600 0 CET}
-    {2974064400 7200 1 CEST}
-    {2992208400 3600 0 CET}
-    {3005514000 7200 1 CEST}
-    {3023658000 3600 0 CET}
-    {3036963600 7200 1 CEST}
-    {3055712400 3600 0 CET}
-    {3068413200 7200 1 CEST}
-    {3087162000 3600 0 CET}
-    {3099862800 7200 1 CEST}
-    {3118611600 3600 0 CET}
-    {3131917200 7200 1 CEST}
-    {3150061200 3600 0 CET}
-    {3163366800 7200 1 CEST}
-    {3181510800 3600 0 CET}
-    {3194816400 7200 1 CEST}
-    {3212960400 3600 0 CET}
-    {3226266000 7200 1 CEST}
-    {3245014800 3600 0 CET}
-    {3257715600 7200 1 CEST}
-    {3276464400 3600 0 CET}
-    {3289165200 7200 1 CEST}
-    {3307914000 3600 0 CET}
-    {3321219600 7200 1 CEST}
-    {3339363600 3600 0 CET}
-    {3352669200 7200 1 CEST}
-    {3370813200 3600 0 CET}
-    {3384118800 7200 1 CEST}
-    {3402867600 3600 0 CET}
-    {3415568400 7200 1 CEST}
-    {3434317200 3600 0 CET}
-    {3447018000 7200 1 CEST}
-    {3465766800 3600 0 CET}
-    {3479072400 7200 1 CEST}
-    {3497216400 3600 0 CET}
-    {3510522000 7200 1 CEST}
-    {3528666000 3600 0 CET}
-    {3541971600 7200 1 CEST}
-    {3560115600 3600 0 CET}
-    {3573421200 7200 1 CEST}
-    {3592170000 3600 0 CET}
-    {3604870800 7200 1 CEST}
-    {3623619600 3600 0 CET}
-    {3636320400 7200 1 CEST}
-    {3655069200 3600 0 CET}
-    {3668374800 7200 1 CEST}
-    {3686518800 3600 0 CET}
-    {3699824400 7200 1 CEST}
-    {3717968400 3600 0 CET}
-    {3731274000 7200 1 CEST}
-    {3750022800 3600 0 CET}
-    {3762723600 7200 1 CEST}
-    {3781472400 3600 0 CET}
-    {3794173200 7200 1 CEST}
-    {3812922000 3600 0 CET}
-    {3825622800 7200 1 CEST}
-    {3844371600 3600 0 CET}
-    {3857677200 7200 1 CEST}
-    {3875821200 3600 0 CET}
-    {3889126800 7200 1 CEST}
-    {3907270800 3600 0 CET}
-    {3920576400 7200 1 CEST}
-    {3939325200 3600 0 CET}
-    {3952026000 7200 1 CEST}
-    {3970774800 3600 0 CET}
-    {3983475600 7200 1 CEST}
-    {4002224400 3600 0 CET}
-    {4015530000 7200 1 CEST}
-    {4033674000 3600 0 CET}
-    {4046979600 7200 1 CEST}
-    {4065123600 3600 0 CET}
-    {4078429200 7200 1 CEST}
-    {4096573200 3600 0 CET}
+if {![info exists TZData(Europe/Berlin)]} {
+    LoadTimeZoneFile Europe/Berlin
 }
+set TZData(:Europe/Copenhagen) $TZData(:Europe/Berlin)
diff --git a/library/tzdata/Europe/Dublin b/library/tzdata/Europe/Dublin
index 56afc93..eb0d182 100644
--- a/library/tzdata/Europe/Dublin
+++ b/library/tzdata/Europe/Dublin
@@ -1,8 +1,8 @@
 # created by tools/tclZIC.tcl - do not edit
 
 set TZData(:Europe/Dublin) {
-    {-9223372036854775808 -1500 0 LMT}
-    {-2821649700 -1521 0 DMT}
+    {-9223372036854775808 -1521 0 LMT}
+    {-2821649679 -1521 0 DMT}
     {-1691962479 2079 1 IST}
     {-1680471279 0 0 GMT}
     {-1664143200 3600 1 BST}
diff --git a/library/tzdata/Europe/Kiev b/library/tzdata/Europe/Kiev
index 8da7061..ac5e50a 100644
--- a/library/tzdata/Europe/Kiev
+++ b/library/tzdata/Europe/Kiev
@@ -1,251 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Europe/Kiev) {
-    {-9223372036854775808 7324 0 LMT}
-    {-2840148124 7324 0 KMT}
-    {-1441159324 7200 0 EET}
-    {-1247536800 10800 0 MSK}
-    {-892522800 3600 0 CET}
-    {-857257200 3600 0 CET}
-    {-844556400 7200 1 CEST}
-    {-828226800 3600 0 CET}
-    {-825382800 10800 0 MSD}
-    {354920400 14400 1 MSD}
-    {370728000 10800 0 MSK}
-    {386456400 14400 1 MSD}
-    {402264000 10800 0 MSK}
-    {417992400 14400 1 MSD}
-    {433800000 10800 0 MSK}
-    {449614800 14400 1 MSD}
-    {465346800 10800 0 MSK}
-    {481071600 14400 1 MSD}
-    {496796400 10800 0 MSK}
-    {512521200 14400 1 MSD}
-    {528246000 10800 0 MSK}
-    {543970800 14400 1 MSD}
-    {559695600 10800 0 MSK}
-    {575420400 14400 1 MSD}
-    {591145200 10800 0 MSK}
-    {606870000 14400 1 MSD}
-    {622594800 10800 0 MSK}
-    {638319600 14400 1 MSD}
-    {646786800 10800 1 EEST}
-    {686102400 7200 0 EET}
-    {701827200 10800 1 EEST}
-    {717552000 7200 0 EET}
-    {733276800 10800 1 EEST}
-    {749001600 7200 0 EET}
-    {764726400 10800 1 EEST}
-    {780451200 7200 0 EET}
-    {796176000 10800 1 EEST}
-    {811900800 7200 0 EET}
-    {828230400 10800 1 EEST}
-    {831938400 10800 0 EEST}
-    {846378000 7200 0 EET}
-    {859683600 10800 1 EEST}
-    {877827600 7200 0 EET}
-    {891133200 10800 1 EEST}
-    {909277200 7200 0 EET}
-    {922582800 10800 1 EEST}
-    {941331600 7200 0 EET}
-    {954032400 10800 1 EEST}
-    {972781200 7200 0 EET}
-    {985482000 10800 1 EEST}
-    {1004230800 7200 0 EET}
-    {1017536400 10800 1 EEST}
-    {1035680400 7200 0 EET}
-    {1048986000 10800 1 EEST}
-    {1067130000 7200 0 EET}
-    {1080435600 10800 1 EEST}
-    {1099184400 7200 0 EET}
-    {1111885200 10800 1 EEST}
-    {1130634000 7200 0 EET}
-    {1143334800 10800 1 EEST}
-    {1162083600 7200 0 EET}
-    {1174784400 10800 1 EEST}
-    {1193533200 7200 0 EET}
-    {1206838800 10800 1 EEST}
-    {1224982800 7200 0 EET}
-    {1238288400 10800 1 EEST}
-    {1256432400 7200 0 EET}
-    {1269738000 10800 1 EEST}
-    {1288486800 7200 0 EET}
-    {1301187600 10800 1 EEST}
-    {1319936400 7200 0 EET}
-    {1332637200 10800 1 EEST}
-    {1351386000 7200 0 EET}
-    {1364691600 10800 1 EEST}
-    {1382835600 7200 0 EET}
-    {1396141200 10800 1 EEST}
-    {1414285200 7200 0 EET}
-    {1427590800 10800 1 EEST}
-    {1445734800 7200 0 EET}
-    {1459040400 10800 1 EEST}
-    {1477789200 7200 0 EET}
-    {1490490000 10800 1 EEST}
-    {1509238800 7200 0 EET}
-    {1521939600 10800 1 EEST}
-    {1540688400 7200 0 EET}
-    {1553994000 10800 1 EEST}
-    {1572138000 7200 0 EET}
-    {1585443600 10800 1 EEST}
-    {1603587600 7200 0 EET}
-    {1616893200 10800 1 EEST}
-    {1635642000 7200 0 EET}
-    {1648342800 10800 1 EEST}
-    {1667091600 7200 0 EET}
-    {1679792400 10800 1 EEST}
-    {1698541200 7200 0 EET}
-    {1711846800 10800 1 EEST}
-    {1729990800 7200 0 EET}
-    {1743296400 10800 1 EEST}
-    {1761440400 7200 0 EET}
-    {1774746000 10800 1 EEST}
-    {1792890000 7200 0 EET}
-    {1806195600 10800 1 EEST}
-    {1824944400 7200 0 EET}
-    {1837645200 10800 1 EEST}
-    {1856394000 7200 0 EET}
-    {1869094800 10800 1 EEST}
-    {1887843600 7200 0 EET}
-    {1901149200 10800 1 EEST}
-    {1919293200 7200 0 EET}
-    {1932598800 10800 1 EEST}
-    {1950742800 7200 0 EET}
-    {1964048400 10800 1 EEST}
-    {1982797200 7200 0 EET}
-    {1995498000 10800 1 EEST}
-    {2014246800 7200 0 EET}
-    {2026947600 10800 1 EEST}
-    {2045696400 7200 0 EET}
-    {2058397200 10800 1 EEST}
-    {2077146000 7200 0 EET}
-    {2090451600 10800 1 EEST}
-    {2108595600 7200 0 EET}
-    {2121901200 10800 1 EEST}
-    {2140045200 7200 0 EET}
-    {2153350800 10800 1 EEST}
-    {2172099600 7200 0 EET}
-    {2184800400 10800 1 EEST}
-    {2203549200 7200 0 EET}
-    {2216250000 10800 1 EEST}
-    {2234998800 7200 0 EET}
-    {2248304400 10800 1 EEST}
-    {2266448400 7200 0 EET}
-    {2279754000 10800 1 EEST}
-    {2297898000 7200 0 EET}
-    {2311203600 10800 1 EEST}
-    {2329347600 7200 0 EET}
-    {2342653200 10800 1 EEST}
-    {2361402000 7200 0 EET}
-    {2374102800 10800 1 EEST}
-    {2392851600 7200 0 EET}
-    {2405552400 10800 1 EEST}
-    {2424301200 7200 0 EET}
-    {2437606800 10800 1 EEST}
-    {2455750800 7200 0 EET}
-    {2469056400 10800 1 EEST}
-    {2487200400 7200 0 EET}
-    {2500506000 10800 1 EEST}
-    {2519254800 7200 0 EET}
-    {2531955600 10800 1 EEST}
-    {2550704400 7200 0 EET}
-    {2563405200 10800 1 EEST}
-    {2582154000 7200 0 EET}
-    {2595459600 10800 1 EEST}
-    {2613603600 7200 0 EET}
-    {2626909200 10800 1 EEST}
-    {2645053200 7200 0 EET}
-    {2658358800 10800 1 EEST}
-    {2676502800 7200 0 EET}
-    {2689808400 10800 1 EEST}
-    {2708557200 7200 0 EET}
-    {2721258000 10800 1 EEST}
-    {2740006800 7200 0 EET}
-    {2752707600 10800 1 EEST}
-    {2771456400 7200 0 EET}
-    {2784762000 10800 1 EEST}
-    {2802906000 7200 0 EET}
-    {2816211600 10800 1 EEST}
-    {2834355600 7200 0 EET}
-    {2847661200 10800 1 EEST}
-    {2866410000 7200 0 EET}
-    {2879110800 10800 1 EEST}
-    {2897859600 7200 0 EET}
-    {2910560400 10800 1 EEST}
-    {2929309200 7200 0 EET}
-    {2942010000 10800 1 EEST}
-    {2960758800 7200 0 EET}
-    {2974064400 10800 1 EEST}
-    {2992208400 7200 0 EET}
-    {3005514000 10800 1 EEST}
-    {3023658000 7200 0 EET}
-    {3036963600 10800 1 EEST}
-    {3055712400 7200 0 EET}
-    {3068413200 10800 1 EEST}
-    {3087162000 7200 0 EET}
-    {3099862800 10800 1 EEST}
-    {3118611600 7200 0 EET}
-    {3131917200 10800 1 EEST}
-    {3150061200 7200 0 EET}
-    {3163366800 10800 1 EEST}
-    {3181510800 7200 0 EET}
-    {3194816400 10800 1 EEST}
-    {3212960400 7200 0 EET}
-    {3226266000 10800 1 EEST}
-    {3245014800 7200 0 EET}
-    {3257715600 10800 1 EEST}
-    {3276464400 7200 0 EET}
-    {3289165200 10800 1 EEST}
-    {3307914000 7200 0 EET}
-    {3321219600 10800 1 EEST}
-    {3339363600 7200 0 EET}
-    {3352669200 10800 1 EEST}
-    {3370813200 7200 0 EET}
-    {3384118800 10800 1 EEST}
-    {3402867600 7200 0 EET}
-    {3415568400 10800 1 EEST}
-    {3434317200 7200 0 EET}
-    {3447018000 10800 1 EEST}
-    {3465766800 7200 0 EET}
-    {3479072400 10800 1 EEST}
-    {3497216400 7200 0 EET}
-    {3510522000 10800 1 EEST}
-    {3528666000 7200 0 EET}
-    {3541971600 10800 1 EEST}
-    {3560115600 7200 0 EET}
-    {3573421200 10800 1 EEST}
-    {3592170000 7200 0 EET}
-    {3604870800 10800 1 EEST}
-    {3623619600 7200 0 EET}
-    {3636320400 10800 1 EEST}
-    {3655069200 7200 0 EET}
-    {3668374800 10800 1 EEST}
-    {3686518800 7200 0 EET}
-    {3699824400 10800 1 EEST}
-    {3717968400 7200 0 EET}
-    {3731274000 10800 1 EEST}
-    {3750022800 7200 0 EET}
-    {3762723600 10800 1 EEST}
-    {3781472400 7200 0 EET}
-    {3794173200 10800 1 EEST}
-    {3812922000 7200 0 EET}
-    {3825622800 10800 1 EEST}
-    {3844371600 7200 0 EET}
-    {3857677200 10800 1 EEST}
-    {3875821200 7200 0 EET}
-    {3889126800 10800 1 EEST}
-    {3907270800 7200 0 EET}
-    {3920576400 10800 1 EEST}
-    {3939325200 7200 0 EET}
-    {3952026000 10800 1 EEST}
-    {3970774800 7200 0 EET}
-    {3983475600 10800 1 EEST}
-    {4002224400 7200 0 EET}
-    {4015530000 10800 1 EEST}
-    {4033674000 7200 0 EET}
-    {4046979600 10800 1 EEST}
-    {4065123600 7200 0 EET}
-    {4078429200 10800 1 EEST}
-    {4096573200 7200 0 EET}
+if {![info exists TZData(Europe/Kyiv)]} {
+    LoadTimeZoneFile Europe/Kyiv
 }
+set TZData(:Europe/Kiev) $TZData(:Europe/Kyiv)
diff --git a/library/tzdata/Europe/Kyiv b/library/tzdata/Europe/Kyiv
new file mode 100644
index 0000000..c7c0e2f
--- /dev/null
+++ b/library/tzdata/Europe/Kyiv
@@ -0,0 +1,251 @@
+# created by tools/tclZIC.tcl - do not edit
+
+set TZData(:Europe/Kyiv) {
+    {-9223372036854775808 7324 0 LMT}
+    {-2840148124 7324 0 KMT}
+    {-1441159324 7200 0 EET}
+    {-1247536800 10800 0 MSK}
+    {-892522800 3600 0 CET}
+    {-857257200 3600 0 CET}
+    {-844556400 7200 1 CEST}
+    {-828226800 3600 0 CET}
+    {-825382800 10800 0 MSD}
+    {354920400 14400 1 MSD}
+    {370728000 10800 0 MSK}
+    {386456400 14400 1 MSD}
+    {402264000 10800 0 MSK}
+    {417992400 14400 1 MSD}
+    {433800000 10800 0 MSK}
+    {449614800 14400 1 MSD}
+    {465346800 10800 0 MSK}
+    {481071600 14400 1 MSD}
+    {496796400 10800 0 MSK}
+    {512521200 14400 1 MSD}
+    {528246000 10800 0 MSK}
+    {543970800 14400 1 MSD}
+    {559695600 10800 0 MSK}
+    {575420400 14400 1 MSD}
+    {591145200 10800 0 MSK}
+    {606870000 14400 1 MSD}
+    {622594800 10800 0 MSK}
+    {638319600 14400 1 MSD}
+    {646786800 10800 1 EEST}
+    {686102400 7200 0 EET}
+    {701827200 10800 1 EEST}
+    {717552000 7200 0 EET}
+    {733276800 10800 1 EEST}
+    {749001600 7200 0 EET}
+    {764726400 10800 1 EEST}
+    {780451200 7200 0 EET}
+    {796176000 10800 1 EEST}
+    {811900800 7200 0 EET}
+    {828230400 10800 1 EEST}
+    {831938400 10800 0 EEST}
+    {846378000 7200 0 EET}
+    {859683600 10800 1 EEST}
+    {877827600 7200 0 EET}
+    {891133200 10800 1 EEST}
+    {909277200 7200 0 EET}
+    {922582800 10800 1 EEST}
+    {941331600 7200 0 EET}
+    {954032400 10800 1 EEST}
+    {972781200 7200 0 EET}
+    {985482000 10800 1 EEST}
+    {1004230800 7200 0 EET}
+    {1017536400 10800 1 EEST}
+    {1035680400 7200 0 EET}
+    {1048986000 10800 1 EEST}
+    {1067130000 7200 0 EET}
+    {1080435600 10800 1 EEST}
+    {1099184400 7200 0 EET}
+    {1111885200 10800 1 EEST}
+    {1130634000 7200 0 EET}
+    {1143334800 10800 1 EEST}
+    {1162083600 7200 0 EET}
+    {1174784400 10800 1 EEST}
+    {1193533200 7200 0 EET}
+    {1206838800 10800 1 EEST}
+    {1224982800 7200 0 EET}
+    {1238288400 10800 1 EEST}
+    {1256432400 7200 0 EET}
+    {1269738000 10800 1 EEST}
+    {1288486800 7200 0 EET}
+    {1301187600 10800 1 EEST}
+    {1319936400 7200 0 EET}
+    {1332637200 10800 1 EEST}
+    {1351386000 7200 0 EET}
+    {1364691600 10800 1 EEST}
+    {1382835600 7200 0 EET}
+    {1396141200 10800 1 EEST}
+    {1414285200 7200 0 EET}
+    {1427590800 10800 1 EEST}
+    {1445734800 7200 0 EET}
+    {1459040400 10800 1 EEST}
+    {1477789200 7200 0 EET}
+    {1490490000 10800 1 EEST}
+    {1509238800 7200 0 EET}
+    {1521939600 10800 1 EEST}
+    {1540688400 7200 0 EET}
+    {1553994000 10800 1 EEST}
+    {1572138000 7200 0 EET}
+    {1585443600 10800 1 EEST}
+    {1603587600 7200 0 EET}
+    {1616893200 10800 1 EEST}
+    {1635642000 7200 0 EET}
+    {1648342800 10800 1 EEST}
+    {1667091600 7200 0 EET}
+    {1679792400 10800 1 EEST}
+    {1698541200 7200 0 EET}
+    {1711846800 10800 1 EEST}
+    {1729990800 7200 0 EET}
+    {1743296400 10800 1 EEST}
+    {1761440400 7200 0 EET}
+    {1774746000 10800 1 EEST}
+    {1792890000 7200 0 EET}
+    {1806195600 10800 1 EEST}
+    {1824944400 7200 0 EET}
+    {1837645200 10800 1 EEST}
+    {1856394000 7200 0 EET}
+    {1869094800 10800 1 EEST}
+    {1887843600 7200 0 EET}
+    {1901149200 10800 1 EEST}
+    {1919293200 7200 0 EET}
+    {1932598800 10800 1 EEST}
+    {1950742800 7200 0 EET}
+    {1964048400 10800 1 EEST}
+    {1982797200 7200 0 EET}
+    {1995498000 10800 1 EEST}
+    {2014246800 7200 0 EET}
+    {2026947600 10800 1 EEST}
+    {2045696400 7200 0 EET}
+    {2058397200 10800 1 EEST}
+    {2077146000 7200 0 EET}
+    {2090451600 10800 1 EEST}
+    {2108595600 7200 0 EET}
+    {2121901200 10800 1 EEST}
+    {2140045200 7200 0 EET}
+    {2153350800 10800 1 EEST}
+    {2172099600 7200 0 EET}
+    {2184800400 10800 1 EEST}
+    {2203549200 7200 0 EET}
+    {2216250000 10800 1 EEST}
+    {2234998800 7200 0 EET}
+    {2248304400 10800 1 EEST}
+    {2266448400 7200 0 EET}
+    {2279754000 10800 1 EEST}
+    {2297898000 7200 0 EET}
+    {2311203600 10800 1 EEST}
+    {2329347600 7200 0 EET}
+    {2342653200 10800 1 EEST}
+    {2361402000 7200 0 EET}
+    {2374102800 10800 1 EEST}
+    {2392851600 7200 0 EET}
+    {2405552400 10800 1 EEST}
+    {2424301200 7200 0 EET}
+    {2437606800 10800 1 EEST}
+    {2455750800 7200 0 EET}
+    {2469056400 10800 1 EEST}
+    {2487200400 7200 0 EET}
+    {2500506000 10800 1 EEST}
+    {2519254800 7200 0 EET}
+    {2531955600 10800 1 EEST}
+    {2550704400 7200 0 EET}
+    {2563405200 10800 1 EEST}
+    {2582154000 7200 0 EET}
+    {2595459600 10800 1 EEST}
+    {2613603600 7200 0 EET}
+    {2626909200 10800 1 EEST}
+    {2645053200 7200 0 EET}
+    {2658358800 10800 1 EEST}
+    {2676502800 7200 0 EET}
+    {2689808400 10800 1 EEST}
+    {2708557200 7200 0 EET}
+    {2721258000 10800 1 EEST}
+    {2740006800 7200 0 EET}
+    {2752707600 10800 1 EEST}
+    {2771456400 7200 0 EET}
+    {2784762000 10800 1 EEST}
+    {2802906000 7200 0 EET}
+    {2816211600 10800 1 EEST}
+    {2834355600 7200 0 EET}
+    {2847661200 10800 1 EEST}
+    {2866410000 7200 0 EET}
+    {2879110800 10800 1 EEST}
+    {2897859600 7200 0 EET}
+    {2910560400 10800 1 EEST}
+    {2929309200 7200 0 EET}
+    {2942010000 10800 1 EEST}
+    {2960758800 7200 0 EET}
+    {2974064400 10800 1 EEST}
+    {2992208400 7200 0 EET}
+    {3005514000 10800 1 EEST}
+    {3023658000 7200 0 EET}
+    {3036963600 10800 1 EEST}
+    {3055712400 7200 0 EET}
+    {3068413200 10800 1 EEST}
+    {3087162000 7200 0 EET}
+    {3099862800 10800 1 EEST}
+    {3118611600 7200 0 EET}
+    {3131917200 10800 1 EEST}
+    {3150061200 7200 0 EET}
+    {3163366800 10800 1 EEST}
+    {3181510800 7200 0 EET}
+    {3194816400 10800 1 EEST}
+    {3212960400 7200 0 EET}
+    {3226266000 10800 1 EEST}
+    {3245014800 7200 0 EET}
+    {3257715600 10800 1 EEST}
+    {3276464400 7200 0 EET}
+    {3289165200 10800 1 EEST}
+    {3307914000 7200 0 EET}
+    {3321219600 10800 1 EEST}
+    {3339363600 7200 0 EET}
+    {3352669200 10800 1 EEST}
+    {3370813200 7200 0 EET}
+    {3384118800 10800 1 EEST}
+    {3402867600 7200 0 EET}
+    {3415568400 10800 1 EEST}
+    {3434317200 7200 0 EET}
+    {3447018000 10800 1 EEST}
+    {3465766800 7200 0 EET}
+    {3479072400 10800 1 EEST}
+    {3497216400 7200 0 EET}
+    {3510522000 10800 1 EEST}
+    {3528666000 7200 0 EET}
+    {3541971600 10800 1 EEST}
+    {3560115600 7200 0 EET}
+    {3573421200 10800 1 EEST}
+    {3592170000 7200 0 EET}
+    {3604870800 10800 1 EEST}
+    {3623619600 7200 0 EET}
+    {3636320400 10800 1 EEST}
+    {3655069200 7200 0 EET}
+    {3668374800 10800 1 EEST}
+    {3686518800 7200 0 EET}
+    {3699824400 10800 1 EEST}
+    {3717968400 7200 0 EET}
+    {3731274000 10800 1 EEST}
+    {3750022800 7200 0 EET}
+    {3762723600 10800 1 EEST}
+    {3781472400 7200 0 EET}
+    {3794173200 10800 1 EEST}
+    {3812922000 7200 0 EET}
+    {3825622800 10800 1 EEST}
+    {3844371600 7200 0 EET}
+    {3857677200 10800 1 EEST}
+    {3875821200 7200 0 EET}
+    {3889126800 10800 1 EEST}
+    {3907270800 7200 0 EET}
+    {3920576400 10800 1 EEST}
+    {3939325200 7200 0 EET}
+    {3952026000 10800 1 EEST}
+    {3970774800 7200 0 EET}
+    {3983475600 10800 1 EEST}
+    {4002224400 7200 0 EET}
+    {4015530000 10800 1 EEST}
+    {4033674000 7200 0 EET}
+    {4046979600 10800 1 EEST}
+    {4065123600 7200 0 EET}
+    {4078429200 10800 1 EEST}
+    {4096573200 7200 0 EET}
+}
diff --git a/library/tzdata/Europe/Luxembourg b/library/tzdata/Europe/Luxembourg
index 2a88c4b..da3ebe2 100644
--- a/library/tzdata/Europe/Luxembourg
+++ b/library/tzdata/Europe/Luxembourg
@@ -1,313 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Europe/Luxembourg) {
-    {-9223372036854775808 1476 0 LMT}
-    {-2069713476 3600 0 CET}
-    {-1692496800 7200 1 CEST}
-    {-1680483600 3600 0 CET}
-    {-1662343200 7200 1 CEST}
-    {-1650157200 3600 0 CET}
-    {-1632006000 7200 1 CEST}
-    {-1618700400 3600 0 CET}
-    {-1612659600 0 0 WET}
-    {-1604278800 3600 1 WEST}
-    {-1585519200 0 0 WET}
-    {-1574038800 3600 1 WEST}
-    {-1552258800 0 0 WET}
-    {-1539997200 3600 1 WEST}
-    {-1520550000 0 0 WET}
-    {-1507510800 3600 1 WEST}
-    {-1490572800 0 0 WET}
-    {-1473642000 3600 1 WEST}
-    {-1459119600 0 0 WET}
-    {-1444006800 3600 1 WEST}
-    {-1427673600 0 0 WET}
-    {-1411866000 3600 1 WEST}
-    {-1396224000 0 0 WET}
-    {-1379293200 3600 1 WEST}
-    {-1364774400 0 0 WET}
-    {-1348448400 3600 1 WEST}
-    {-1333324800 0 0 WET}
-    {-1316394000 3600 1 WEST}
-    {-1301270400 0 0 WET}
-    {-1284339600 3600 1 WEST}
-    {-1269813600 0 0 WET}
-    {-1253484000 3600 1 WEST}
-    {-1238364000 0 0 WET}
-    {-1221429600 3600 1 WEST}
-    {-1206914400 0 0 WET}
-    {-1191189600 3600 1 WEST}
-    {-1175464800 0 0 WET}
-    {-1160344800 3600 1 WEST}
-    {-1143410400 0 0 WET}
-    {-1127685600 3600 1 WEST}
-    {-1111960800 0 0 WET}
-    {-1096840800 3600 1 WEST}
-    {-1080511200 0 0 WET}
-    {-1063576800 3600 1 WEST}
-    {-1049061600 0 0 WET}
-    {-1033336800 3600 1 WEST}
-    {-1017612000 0 0 WET}
-    {-1002492000 3600 1 WEST}
-    {-986162400 0 0 WET}
-    {-969228000 3600 1 WEST}
-    {-950479200 0 0 WET}
-    {-942012000 3600 1 WEST}
-    {-935186400 7200 0 WEST}
-    {-857257200 3600 0 WET}
-    {-844556400 7200 1 WEST}
-    {-828226800 3600 0 WET}
-    {-812502000 7200 1 WEST}
-    {-797983200 3600 0 CET}
-    {-781052400 7200 1 CEST}
-    {-766623600 3600 0 CET}
-    {-745455600 7200 1 CEST}
-    {-733273200 3600 0 CET}
-    {220921200 3600 0 CET}
-    {228877200 7200 1 CEST}
-    {243997200 3600 0 CET}
-    {260326800 7200 1 CEST}
-    {276051600 3600 0 CET}
-    {291776400 7200 1 CEST}
-    {307501200 3600 0 CET}
-    {323830800 7200 1 CEST}
-    {338950800 3600 0 CET}
-    {354675600 7200 1 CEST}
-    {370400400 3600 0 CET}
-    {386125200 7200 1 CEST}
-    {401850000 3600 0 CET}
-    {417574800 7200 1 CEST}
-    {433299600 3600 0 CET}
-    {449024400 7200 1 CEST}
-    {465354000 3600 0 CET}
-    {481078800 7200 1 CEST}
-    {496803600 3600 0 CET}
-    {512528400 7200 1 CEST}
-    {528253200 3600 0 CET}
-    {543978000 7200 1 CEST}
-    {559702800 3600 0 CET}
-    {575427600 7200 1 CEST}
-    {591152400 3600 0 CET}
-    {606877200 7200 1 CEST}
-    {622602000 3600 0 CET}
-    {638326800 7200 1 CEST}
-    {654656400 3600 0 CET}
-    {670381200 7200 1 CEST}
-    {686106000 3600 0 CET}
-    {701830800 7200 1 CEST}
-    {717555600 3600 0 CET}
-    {733280400 7200 1 CEST}
-    {749005200 3600 0 CET}
-    {764730000 7200 1 CEST}
-    {780454800 3600 0 CET}
-    {796179600 7200 1 CEST}
-    {811904400 3600 0 CET}
-    {828234000 7200 1 CEST}
-    {846378000 3600 0 CET}
-    {859683600 7200 1 CEST}
-    {877827600 3600 0 CET}
-    {891133200 7200 1 CEST}
-    {909277200 3600 0 CET}
-    {922582800 7200 1 CEST}
-    {941331600 3600 0 CET}
-    {954032400 7200 1 CEST}
-    {972781200 3600 0 CET}
-    {985482000 7200 1 CEST}
-    {1004230800 3600 0 CET}
-    {1017536400 7200 1 CEST}
-    {1035680400 3600 0 CET}
-    {1048986000 7200 1 CEST}
-    {1067130000 3600 0 CET}
-    {1080435600 7200 1 CEST}
-    {1099184400 3600 0 CET}
-    {1111885200 7200 1 CEST}
-    {1130634000 3600 0 CET}
-    {1143334800 7200 1 CEST}
-    {1162083600 3600 0 CET}
-    {1174784400 7200 1 CEST}
-    {1193533200 3600 0 CET}
-    {1206838800 7200 1 CEST}
-    {1224982800 3600 0 CET}
-    {1238288400 7200 1 CEST}
-    {1256432400 3600 0 CET}
-    {1269738000 7200 1 CEST}
-    {1288486800 3600 0 CET}
-    {1301187600 7200 1 CEST}
-    {1319936400 3600 0 CET}
-    {1332637200 7200 1 CEST}
-    {1351386000 3600 0 CET}
-    {1364691600 7200 1 CEST}
-    {1382835600 3600 0 CET}
-    {1396141200 7200 1 CEST}
-    {1414285200 3600 0 CET}
-    {1427590800 7200 1 CEST}
-    {1445734800 3600 0 CET}
-    {1459040400 7200 1 CEST}
-    {1477789200 3600 0 CET}
-    {1490490000 7200 1 CEST}
-    {1509238800 3600 0 CET}
-    {1521939600 7200 1 CEST}
-    {1540688400 3600 0 CET}
-    {1553994000 7200 1 CEST}
-    {1572138000 3600 0 CET}
-    {1585443600 7200 1 CEST}
-    {1603587600 3600 0 CET}
-    {1616893200 7200 1 CEST}
-    {1635642000 3600 0 CET}
-    {1648342800 7200 1 CEST}
-    {1667091600 3600 0 CET}
-    {1679792400 7200 1 CEST}
-    {1698541200 3600 0 CET}
-    {1711846800 7200 1 CEST}
-    {1729990800 3600 0 CET}
-    {1743296400 7200 1 CEST}
-    {1761440400 3600 0 CET}
-    {1774746000 7200 1 CEST}
-    {1792890000 3600 0 CET}
-    {1806195600 7200 1 CEST}
-    {1824944400 3600 0 CET}
-    {1837645200 7200 1 CEST}
-    {1856394000 3600 0 CET}
-    {1869094800 7200 1 CEST}
-    {1887843600 3600 0 CET}
-    {1901149200 7200 1 CEST}
-    {1919293200 3600 0 CET}
-    {1932598800 7200 1 CEST}
-    {1950742800 3600 0 CET}
-    {1964048400 7200 1 CEST}
-    {1982797200 3600 0 CET}
-    {1995498000 7200 1 CEST}
-    {2014246800 3600 0 CET}
-    {2026947600 7200 1 CEST}
-    {2045696400 3600 0 CET}
-    {2058397200 7200 1 CEST}
-    {2077146000 3600 0 CET}
-    {2090451600 7200 1 CEST}
-    {2108595600 3600 0 CET}
-    {2121901200 7200 1 CEST}
-    {2140045200 3600 0 CET}
-    {2153350800 7200 1 CEST}
-    {2172099600 3600 0 CET}
-    {2184800400 7200 1 CEST}
-    {2203549200 3600 0 CET}
-    {2216250000 7200 1 CEST}
-    {2234998800 3600 0 CET}
-    {2248304400 7200 1 CEST}
-    {2266448400 3600 0 CET}
-    {2279754000 7200 1 CEST}
-    {2297898000 3600 0 CET}
-    {2311203600 7200 1 CEST}
-    {2329347600 3600 0 CET}
-    {2342653200 7200 1 CEST}
-    {2361402000 3600 0 CET}
-    {2374102800 7200 1 CEST}
-    {2392851600 3600 0 CET}
-    {2405552400 7200 1 CEST}
-    {2424301200 3600 0 CET}
-    {2437606800 7200 1 CEST}
-    {2455750800 3600 0 CET}
-    {2469056400 7200 1 CEST}
-    {2487200400 3600 0 CET}
-    {2500506000 7200 1 CEST}
-    {2519254800 3600 0 CET}
-    {2531955600 7200 1 CEST}
-    {2550704400 3600 0 CET}
-    {2563405200 7200 1 CEST}
-    {2582154000 3600 0 CET}
-    {2595459600 7200 1 CEST}
-    {2613603600 3600 0 CET}
-    {2626909200 7200 1 CEST}
-    {2645053200 3600 0 CET}
-    {2658358800 7200 1 CEST}
-    {2676502800 3600 0 CET}
-    {2689808400 7200 1 CEST}
-    {2708557200 3600 0 CET}
-    {2721258000 7200 1 CEST}
-    {2740006800 3600 0 CET}
-    {2752707600 7200 1 CEST}
-    {2771456400 3600 0 CET}
-    {2784762000 7200 1 CEST}
-    {2802906000 3600 0 CET}
-    {2816211600 7200 1 CEST}
-    {2834355600 3600 0 CET}
-    {2847661200 7200 1 CEST}
-    {2866410000 3600 0 CET}
-    {2879110800 7200 1 CEST}
-    {2897859600 3600 0 CET}
-    {2910560400 7200 1 CEST}
-    {2929309200 3600 0 CET}
-    {2942010000 7200 1 CEST}
-    {2960758800 3600 0 CET}
-    {2974064400 7200 1 CEST}
-    {2992208400 3600 0 CET}
-    {3005514000 7200 1 CEST}
-    {3023658000 3600 0 CET}
-    {3036963600 7200 1 CEST}
-    {3055712400 3600 0 CET}
-    {3068413200 7200 1 CEST}
-    {3087162000 3600 0 CET}
-    {3099862800 7200 1 CEST}
-    {3118611600 3600 0 CET}
-    {3131917200 7200 1 CEST}
-    {3150061200 3600 0 CET}
-    {3163366800 7200 1 CEST}
-    {3181510800 3600 0 CET}
-    {3194816400 7200 1 CEST}
-    {3212960400 3600 0 CET}
-    {3226266000 7200 1 CEST}
-    {3245014800 3600 0 CET}
-    {3257715600 7200 1 CEST}
-    {3276464400 3600 0 CET}
-    {3289165200 7200 1 CEST}
-    {3307914000 3600 0 CET}
-    {3321219600 7200 1 CEST}
-    {3339363600 3600 0 CET}
-    {3352669200 7200 1 CEST}
-    {3370813200 3600 0 CET}
-    {3384118800 7200 1 CEST}
-    {3402867600 3600 0 CET}
-    {3415568400 7200 1 CEST}
-    {3434317200 3600 0 CET}
-    {3447018000 7200 1 CEST}
-    {3465766800 3600 0 CET}
-    {3479072400 7200 1 CEST}
-    {3497216400 3600 0 CET}
-    {3510522000 7200 1 CEST}
-    {3528666000 3600 0 CET}
-    {3541971600 7200 1 CEST}
-    {3560115600 3600 0 CET}
-    {3573421200 7200 1 CEST}
-    {3592170000 3600 0 CET}
-    {3604870800 7200 1 CEST}
-    {3623619600 3600 0 CET}
-    {3636320400 7200 1 CEST}
-    {3655069200 3600 0 CET}
-    {3668374800 7200 1 CEST}
-    {3686518800 3600 0 CET}
-    {3699824400 7200 1 CEST}
-    {3717968400 3600 0 CET}
-    {3731274000 7200 1 CEST}
-    {3750022800 3600 0 CET}
-    {3762723600 7200 1 CEST}
-    {3781472400 3600 0 CET}
-    {3794173200 7200 1 CEST}
-    {3812922000 3600 0 CET}
-    {3825622800 7200 1 CEST}
-    {3844371600 3600 0 CET}
-    {3857677200 7200 1 CEST}
-    {3875821200 3600 0 CET}
-    {3889126800 7200 1 CEST}
-    {3907270800 3600 0 CET}
-    {3920576400 7200 1 CEST}
-    {3939325200 3600 0 CET}
-    {3952026000 7200 1 CEST}
-    {3970774800 3600 0 CET}
-    {3983475600 7200 1 CEST}
-    {4002224400 3600 0 CET}
-    {4015530000 7200 1 CEST}
-    {4033674000 3600 0 CET}
-    {4046979600 7200 1 CEST}
-    {4065123600 3600 0 CET}
-    {4078429200 7200 1 CEST}
-    {4096573200 3600 0 CET}
+if {![info exists TZData(Europe/Brussels)]} {
+    LoadTimeZoneFile Europe/Brussels
 }
+set TZData(:Europe/Luxembourg) $TZData(:Europe/Brussels)
diff --git a/library/tzdata/Europe/Monaco b/library/tzdata/Europe/Monaco
index 7428b2f..54f9d27 100644
--- a/library/tzdata/Europe/Monaco
+++ b/library/tzdata/Europe/Monaco
@@ -1,315 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Europe/Monaco) {
-    {-9223372036854775808 1772 0 LMT}
-    {-2448318572 561 0 PMT}
-    {-1854403761 0 0 WET}
-    {-1689814800 3600 1 WEST}
-    {-1680397200 0 0 WET}
-    {-1665363600 3600 1 WEST}
-    {-1648342800 0 0 WET}
-    {-1635123600 3600 1 WEST}
-    {-1616893200 0 0 WET}
-    {-1604278800 3600 1 WEST}
-    {-1585443600 0 0 WET}
-    {-1574038800 3600 1 WEST}
-    {-1552266000 0 0 WET}
-    {-1539997200 3600 1 WEST}
-    {-1520557200 0 0 WET}
-    {-1507510800 3600 1 WEST}
-    {-1490576400 0 0 WET}
-    {-1470618000 3600 1 WEST}
-    {-1459126800 0 0 WET}
-    {-1444006800 3600 1 WEST}
-    {-1427677200 0 0 WET}
-    {-1411952400 3600 1 WEST}
-    {-1396227600 0 0 WET}
-    {-1379293200 3600 1 WEST}
-    {-1364778000 0 0 WET}
-    {-1348448400 3600 1 WEST}
-    {-1333328400 0 0 WET}
-    {-1316394000 3600 1 WEST}
-    {-1301274000 0 0 WET}
-    {-1284339600 3600 1 WEST}
-    {-1269824400 0 0 WET}
-    {-1253494800 3600 1 WEST}
-    {-1238374800 0 0 WET}
-    {-1221440400 3600 1 WEST}
-    {-1206925200 0 0 WET}
-    {-1191200400 3600 1 WEST}
-    {-1175475600 0 0 WET}
-    {-1160355600 3600 1 WEST}
-    {-1143421200 0 0 WET}
-    {-1127696400 3600 1 WEST}
-    {-1111971600 0 0 WET}
-    {-1096851600 3600 1 WEST}
-    {-1080522000 0 0 WET}
-    {-1063587600 3600 1 WEST}
-    {-1049072400 0 0 WET}
-    {-1033347600 3600 1 WEST}
-    {-1017622800 0 0 WET}
-    {-1002502800 3600 1 WEST}
-    {-986173200 0 0 WET}
-    {-969238800 3600 1 WEST}
-    {-950490000 0 0 WET}
-    {-942012000 3600 1 WEST}
-    {-904438800 7200 1 WEMT}
-    {-891136800 3600 1 WEST}
-    {-877827600 7200 1 WEMT}
-    {-857257200 3600 1 WEST}
-    {-844556400 7200 1 WEMT}
-    {-828226800 3600 1 WEST}
-    {-812502000 7200 1 WEMT}
-    {-796266000 3600 1 WEST}
-    {-781052400 7200 1 WEMT}
-    {-766616400 3600 0 CET}
-    {196819200 7200 1 CEST}
-    {212540400 3600 0 CET}
-    {220921200 3600 0 CET}
-    {228877200 7200 1 CEST}
-    {243997200 3600 0 CET}
-    {260326800 7200 1 CEST}
-    {276051600 3600 0 CET}
-    {291776400 7200 1 CEST}
-    {307501200 3600 0 CET}
-    {323830800 7200 1 CEST}
-    {338950800 3600 0 CET}
-    {354675600 7200 1 CEST}
-    {370400400 3600 0 CET}
-    {386125200 7200 1 CEST}
-    {401850000 3600 0 CET}
-    {417574800 7200 1 CEST}
-    {433299600 3600 0 CET}
-    {449024400 7200 1 CEST}
-    {465354000 3600 0 CET}
-    {481078800 7200 1 CEST}
-    {496803600 3600 0 CET}
-    {512528400 7200 1 CEST}
-    {528253200 3600 0 CET}
-    {543978000 7200 1 CEST}
-    {559702800 3600 0 CET}
-    {575427600 7200 1 CEST}
-    {591152400 3600 0 CET}
-    {606877200 7200 1 CEST}
-    {622602000 3600 0 CET}
-    {638326800 7200 1 CEST}
-    {654656400 3600 0 CET}
-    {670381200 7200 1 CEST}
-    {686106000 3600 0 CET}
-    {701830800 7200 1 CEST}
-    {717555600 3600 0 CET}
-    {733280400 7200 1 CEST}
-    {749005200 3600 0 CET}
-    {764730000 7200 1 CEST}
-    {780454800 3600 0 CET}
-    {796179600 7200 1 CEST}
-    {811904400 3600 0 CET}
-    {828234000 7200 1 CEST}
-    {846378000 3600 0 CET}
-    {859683600 7200 1 CEST}
-    {877827600 3600 0 CET}
-    {891133200 7200 1 CEST}
-    {909277200 3600 0 CET}
-    {922582800 7200 1 CEST}
-    {941331600 3600 0 CET}
-    {954032400 7200 1 CEST}
-    {972781200 3600 0 CET}
-    {985482000 7200 1 CEST}
-    {1004230800 3600 0 CET}
-    {1017536400 7200 1 CEST}
-    {1035680400 3600 0 CET}
-    {1048986000 7200 1 CEST}
-    {1067130000 3600 0 CET}
-    {1080435600 7200 1 CEST}
-    {1099184400 3600 0 CET}
-    {1111885200 7200 1 CEST}
-    {1130634000 3600 0 CET}
-    {1143334800 7200 1 CEST}
-    {1162083600 3600 0 CET}
-    {1174784400 7200 1 CEST}
-    {1193533200 3600 0 CET}
-    {1206838800 7200 1 CEST}
-    {1224982800 3600 0 CET}
-    {1238288400 7200 1 CEST}
-    {1256432400 3600 0 CET}
-    {1269738000 7200 1 CEST}
-    {1288486800 3600 0 CET}
-    {1301187600 7200 1 CEST}
-    {1319936400 3600 0 CET}
-    {1332637200 7200 1 CEST}
-    {1351386000 3600 0 CET}
-    {1364691600 7200 1 CEST}
-    {1382835600 3600 0 CET}
-    {1396141200 7200 1 CEST}
-    {1414285200 3600 0 CET}
-    {1427590800 7200 1 CEST}
-    {1445734800 3600 0 CET}
-    {1459040400 7200 1 CEST}
-    {1477789200 3600 0 CET}
-    {1490490000 7200 1 CEST}
-    {1509238800 3600 0 CET}
-    {1521939600 7200 1 CEST}
-    {1540688400 3600 0 CET}
-    {1553994000 7200 1 CEST}
-    {1572138000 3600 0 CET}
-    {1585443600 7200 1 CEST}
-    {1603587600 3600 0 CET}
-    {1616893200 7200 1 CEST}
-    {1635642000 3600 0 CET}
-    {1648342800 7200 1 CEST}
-    {1667091600 3600 0 CET}
-    {1679792400 7200 1 CEST}
-    {1698541200 3600 0 CET}
-    {1711846800 7200 1 CEST}
-    {1729990800 3600 0 CET}
-    {1743296400 7200 1 CEST}
-    {1761440400 3600 0 CET}
-    {1774746000 7200 1 CEST}
-    {1792890000 3600 0 CET}
-    {1806195600 7200 1 CEST}
-    {1824944400 3600 0 CET}
-    {1837645200 7200 1 CEST}
-    {1856394000 3600 0 CET}
-    {1869094800 7200 1 CEST}
-    {1887843600 3600 0 CET}
-    {1901149200 7200 1 CEST}
-    {1919293200 3600 0 CET}
-    {1932598800 7200 1 CEST}
-    {1950742800 3600 0 CET}
-    {1964048400 7200 1 CEST}
-    {1982797200 3600 0 CET}
-    {1995498000 7200 1 CEST}
-    {2014246800 3600 0 CET}
-    {2026947600 7200 1 CEST}
-    {2045696400 3600 0 CET}
-    {2058397200 7200 1 CEST}
-    {2077146000 3600 0 CET}
-    {2090451600 7200 1 CEST}
-    {2108595600 3600 0 CET}
-    {2121901200 7200 1 CEST}
-    {2140045200 3600 0 CET}
-    {2153350800 7200 1 CEST}
-    {2172099600 3600 0 CET}
-    {2184800400 7200 1 CEST}
-    {2203549200 3600 0 CET}
-    {2216250000 7200 1 CEST}
-    {2234998800 3600 0 CET}
-    {2248304400 7200 1 CEST}
-    {2266448400 3600 0 CET}
-    {2279754000 7200 1 CEST}
-    {2297898000 3600 0 CET}
-    {2311203600 7200 1 CEST}
-    {2329347600 3600 0 CET}
-    {2342653200 7200 1 CEST}
-    {2361402000 3600 0 CET}
-    {2374102800 7200 1 CEST}
-    {2392851600 3600 0 CET}
-    {2405552400 7200 1 CEST}
-    {2424301200 3600 0 CET}
-    {2437606800 7200 1 CEST}
-    {2455750800 3600 0 CET}
-    {2469056400 7200 1 CEST}
-    {2487200400 3600 0 CET}
-    {2500506000 7200 1 CEST}
-    {2519254800 3600 0 CET}
-    {2531955600 7200 1 CEST}
-    {2550704400 3600 0 CET}
-    {2563405200 7200 1 CEST}
-    {2582154000 3600 0 CET}
-    {2595459600 7200 1 CEST}
-    {2613603600 3600 0 CET}
-    {2626909200 7200 1 CEST}
-    {2645053200 3600 0 CET}
-    {2658358800 7200 1 CEST}
-    {2676502800 3600 0 CET}
-    {2689808400 7200 1 CEST}
-    {2708557200 3600 0 CET}
-    {2721258000 7200 1 CEST}
-    {2740006800 3600 0 CET}
-    {2752707600 7200 1 CEST}
-    {2771456400 3600 0 CET}
-    {2784762000 7200 1 CEST}
-    {2802906000 3600 0 CET}
-    {2816211600 7200 1 CEST}
-    {2834355600 3600 0 CET}
-    {2847661200 7200 1 CEST}
-    {2866410000 3600 0 CET}
-    {2879110800 7200 1 CEST}
-    {2897859600 3600 0 CET}
-    {2910560400 7200 1 CEST}
-    {2929309200 3600 0 CET}
-    {2942010000 7200 1 CEST}
-    {2960758800 3600 0 CET}
-    {2974064400 7200 1 CEST}
-    {2992208400 3600 0 CET}
-    {3005514000 7200 1 CEST}
-    {3023658000 3600 0 CET}
-    {3036963600 7200 1 CEST}
-    {3055712400 3600 0 CET}
-    {3068413200 7200 1 CEST}
-    {3087162000 3600 0 CET}
-    {3099862800 7200 1 CEST}
-    {3118611600 3600 0 CET}
-    {3131917200 7200 1 CEST}
-    {3150061200 3600 0 CET}
-    {3163366800 7200 1 CEST}
-    {3181510800 3600 0 CET}
-    {3194816400 7200 1 CEST}
-    {3212960400 3600 0 CET}
-    {3226266000 7200 1 CEST}
-    {3245014800 3600 0 CET}
-    {3257715600 7200 1 CEST}
-    {3276464400 3600 0 CET}
-    {3289165200 7200 1 CEST}
-    {3307914000 3600 0 CET}
-    {3321219600 7200 1 CEST}
-    {3339363600 3600 0 CET}
-    {3352669200 7200 1 CEST}
-    {3370813200 3600 0 CET}
-    {3384118800 7200 1 CEST}
-    {3402867600 3600 0 CET}
-    {3415568400 7200 1 CEST}
-    {3434317200 3600 0 CET}
-    {3447018000 7200 1 CEST}
-    {3465766800 3600 0 CET}
-    {3479072400 7200 1 CEST}
-    {3497216400 3600 0 CET}
-    {3510522000 7200 1 CEST}
-    {3528666000 3600 0 CET}
-    {3541971600 7200 1 CEST}
-    {3560115600 3600 0 CET}
-    {3573421200 7200 1 CEST}
-    {3592170000 3600 0 CET}
-    {3604870800 7200 1 CEST}
-    {3623619600 3600 0 CET}
-    {3636320400 7200 1 CEST}
-    {3655069200 3600 0 CET}
-    {3668374800 7200 1 CEST}
-    {3686518800 3600 0 CET}
-    {3699824400 7200 1 CEST}
-    {3717968400 3600 0 CET}
-    {3731274000 7200 1 CEST}
-    {3750022800 3600 0 CET}
-    {3762723600 7200 1 CEST}
-    {3781472400 3600 0 CET}
-    {3794173200 7200 1 CEST}
-    {3812922000 3600 0 CET}
-    {3825622800 7200 1 CEST}
-    {3844371600 3600 0 CET}
-    {3857677200 7200 1 CEST}
-    {3875821200 3600 0 CET}
-    {3889126800 7200 1 CEST}
-    {3907270800 3600 0 CET}
-    {3920576400 7200 1 CEST}
-    {3939325200 3600 0 CET}
-    {3952026000 7200 1 CEST}
-    {3970774800 3600 0 CET}
-    {3983475600 7200 1 CEST}
-    {4002224400 3600 0 CET}
-    {4015530000 7200 1 CEST}
-    {4033674000 3600 0 CET}
-    {4046979600 7200 1 CEST}
-    {4065123600 3600 0 CET}
-    {4078429200 7200 1 CEST}
-    {4096573200 3600 0 CET}
+if {![info exists TZData(Europe/Paris)]} {
+    LoadTimeZoneFile Europe/Paris
 }
+set TZData(:Europe/Monaco) $TZData(:Europe/Paris)
diff --git a/library/tzdata/Europe/Oslo b/library/tzdata/Europe/Oslo
index 6787c1e..d6d564d 100644
--- a/library/tzdata/Europe/Oslo
+++ b/library/tzdata/Europe/Oslo
@@ -1,271 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Europe/Oslo) {
-    {-9223372036854775808 2580 0 LMT}
-    {-2366757780 3600 0 CET}
-    {-1691884800 7200 1 CEST}
-    {-1680573600 3600 0 CET}
-    {-927511200 7200 0 CEST}
-    {-857257200 3600 0 CET}
-    {-844556400 7200 1 CEST}
-    {-828226800 3600 0 CET}
-    {-812502000 7200 1 CEST}
-    {-796777200 3600 0 CET}
-    {-781052400 7200 0 CEST}
-    {-765327600 3600 0 CET}
-    {-340844400 7200 1 CEST}
-    {-324514800 3600 0 CET}
-    {-308790000 7200 1 CEST}
-    {-293065200 3600 0 CET}
-    {-277340400 7200 1 CEST}
-    {-261615600 3600 0 CET}
-    {-245890800 7200 1 CEST}
-    {-230166000 3600 0 CET}
-    {-214441200 7200 1 CEST}
-    {-198716400 3600 0 CET}
-    {-182991600 7200 1 CEST}
-    {-166662000 3600 0 CET}
-    {-147913200 7200 1 CEST}
-    {-135212400 3600 0 CET}
-    {315529200 3600 0 CET}
-    {323830800 7200 1 CEST}
-    {338950800 3600 0 CET}
-    {354675600 7200 1 CEST}
-    {370400400 3600 0 CET}
-    {386125200 7200 1 CEST}
-    {401850000 3600 0 CET}
-    {417574800 7200 1 CEST}
-    {433299600 3600 0 CET}
-    {449024400 7200 1 CEST}
-    {465354000 3600 0 CET}
-    {481078800 7200 1 CEST}
-    {496803600 3600 0 CET}
-    {512528400 7200 1 CEST}
-    {528253200 3600 0 CET}
-    {543978000 7200 1 CEST}
-    {559702800 3600 0 CET}
-    {575427600 7200 1 CEST}
-    {591152400 3600 0 CET}
-    {606877200 7200 1 CEST}
-    {622602000 3600 0 CET}
-    {638326800 7200 1 CEST}
-    {654656400 3600 0 CET}
-    {670381200 7200 1 CEST}
-    {686106000 3600 0 CET}
-    {701830800 7200 1 CEST}
-    {717555600 3600 0 CET}
-    {733280400 7200 1 CEST}
-    {749005200 3600 0 CET}
-    {764730000 7200 1 CEST}
-    {780454800 3600 0 CET}
-    {796179600 7200 1 CEST}
-    {811904400 3600 0 CET}
-    {828234000 7200 1 CEST}
-    {846378000 3600 0 CET}
-    {859683600 7200 1 CEST}
-    {877827600 3600 0 CET}
-    {891133200 7200 1 CEST}
-    {909277200 3600 0 CET}
-    {922582800 7200 1 CEST}
-    {941331600 3600 0 CET}
-    {954032400 7200 1 CEST}
-    {972781200 3600 0 CET}
-    {985482000 7200 1 CEST}
-    {1004230800 3600 0 CET}
-    {1017536400 7200 1 CEST}
-    {1035680400 3600 0 CET}
-    {1048986000 7200 1 CEST}
-    {1067130000 3600 0 CET}
-    {1080435600 7200 1 CEST}
-    {1099184400 3600 0 CET}
-    {1111885200 7200 1 CEST}
-    {1130634000 3600 0 CET}
-    {1143334800 7200 1 CEST}
-    {1162083600 3600 0 CET}
-    {1174784400 7200 1 CEST}
-    {1193533200 3600 0 CET}
-    {1206838800 7200 1 CEST}
-    {1224982800 3600 0 CET}
-    {1238288400 7200 1 CEST}
-    {1256432400 3600 0 CET}
-    {1269738000 7200 1 CEST}
-    {1288486800 3600 0 CET}
-    {1301187600 7200 1 CEST}
-    {1319936400 3600 0 CET}
-    {1332637200 7200 1 CEST}
-    {1351386000 3600 0 CET}
-    {1364691600 7200 1 CEST}
-    {1382835600 3600 0 CET}
-    {1396141200 7200 1 CEST}
-    {1414285200 3600 0 CET}
-    {1427590800 7200 1 CEST}
-    {1445734800 3600 0 CET}
-    {1459040400 7200 1 CEST}
-    {1477789200 3600 0 CET}
-    {1490490000 7200 1 CEST}
-    {1509238800 3600 0 CET}
-    {1521939600 7200 1 CEST}
-    {1540688400 3600 0 CET}
-    {1553994000 7200 1 CEST}
-    {1572138000 3600 0 CET}
-    {1585443600 7200 1 CEST}
-    {1603587600 3600 0 CET}
-    {1616893200 7200 1 CEST}
-    {1635642000 3600 0 CET}
-    {1648342800 7200 1 CEST}
-    {1667091600 3600 0 CET}
-    {1679792400 7200 1 CEST}
-    {1698541200 3600 0 CET}
-    {1711846800 7200 1 CEST}
-    {1729990800 3600 0 CET}
-    {1743296400 7200 1 CEST}
-    {1761440400 3600 0 CET}
-    {1774746000 7200 1 CEST}
-    {1792890000 3600 0 CET}
-    {1806195600 7200 1 CEST}
-    {1824944400 3600 0 CET}
-    {1837645200 7200 1 CEST}
-    {1856394000 3600 0 CET}
-    {1869094800 7200 1 CEST}
-    {1887843600 3600 0 CET}
-    {1901149200 7200 1 CEST}
-    {1919293200 3600 0 CET}
-    {1932598800 7200 1 CEST}
-    {1950742800 3600 0 CET}
-    {1964048400 7200 1 CEST}
-    {1982797200 3600 0 CET}
-    {1995498000 7200 1 CEST}
-    {2014246800 3600 0 CET}
-    {2026947600 7200 1 CEST}
-    {2045696400 3600 0 CET}
-    {2058397200 7200 1 CEST}
-    {2077146000 3600 0 CET}
-    {2090451600 7200 1 CEST}
-    {2108595600 3600 0 CET}
-    {2121901200 7200 1 CEST}
-    {2140045200 3600 0 CET}
-    {2153350800 7200 1 CEST}
-    {2172099600 3600 0 CET}
-    {2184800400 7200 1 CEST}
-    {2203549200 3600 0 CET}
-    {2216250000 7200 1 CEST}
-    {2234998800 3600 0 CET}
-    {2248304400 7200 1 CEST}
-    {2266448400 3600 0 CET}
-    {2279754000 7200 1 CEST}
-    {2297898000 3600 0 CET}
-    {2311203600 7200 1 CEST}
-    {2329347600 3600 0 CET}
-    {2342653200 7200 1 CEST}
-    {2361402000 3600 0 CET}
-    {2374102800 7200 1 CEST}
-    {2392851600 3600 0 CET}
-    {2405552400 7200 1 CEST}
-    {2424301200 3600 0 CET}
-    {2437606800 7200 1 CEST}
-    {2455750800 3600 0 CET}
-    {2469056400 7200 1 CEST}
-    {2487200400 3600 0 CET}
-    {2500506000 7200 1 CEST}
-    {2519254800 3600 0 CET}
-    {2531955600 7200 1 CEST}
-    {2550704400 3600 0 CET}
-    {2563405200 7200 1 CEST}
-    {2582154000 3600 0 CET}
-    {2595459600 7200 1 CEST}
-    {2613603600 3600 0 CET}
-    {2626909200 7200 1 CEST}
-    {2645053200 3600 0 CET}
-    {2658358800 7200 1 CEST}
-    {2676502800 3600 0 CET}
-    {2689808400 7200 1 CEST}
-    {2708557200 3600 0 CET}
-    {2721258000 7200 1 CEST}
-    {2740006800 3600 0 CET}
-    {2752707600 7200 1 CEST}
-    {2771456400 3600 0 CET}
-    {2784762000 7200 1 CEST}
-    {2802906000 3600 0 CET}
-    {2816211600 7200 1 CEST}
-    {2834355600 3600 0 CET}
-    {2847661200 7200 1 CEST}
-    {2866410000 3600 0 CET}
-    {2879110800 7200 1 CEST}
-    {2897859600 3600 0 CET}
-    {2910560400 7200 1 CEST}
-    {2929309200 3600 0 CET}
-    {2942010000 7200 1 CEST}
-    {2960758800 3600 0 CET}
-    {2974064400 7200 1 CEST}
-    {2992208400 3600 0 CET}
-    {3005514000 7200 1 CEST}
-    {3023658000 3600 0 CET}
-    {3036963600 7200 1 CEST}
-    {3055712400 3600 0 CET}
-    {3068413200 7200 1 CEST}
-    {3087162000 3600 0 CET}
-    {3099862800 7200 1 CEST}
-    {3118611600 3600 0 CET}
-    {3131917200 7200 1 CEST}
-    {3150061200 3600 0 CET}
-    {3163366800 7200 1 CEST}
-    {3181510800 3600 0 CET}
-    {3194816400 7200 1 CEST}
-    {3212960400 3600 0 CET}
-    {3226266000 7200 1 CEST}
-    {3245014800 3600 0 CET}
-    {3257715600 7200 1 CEST}
-    {3276464400 3600 0 CET}
-    {3289165200 7200 1 CEST}
-    {3307914000 3600 0 CET}
-    {3321219600 7200 1 CEST}
-    {3339363600 3600 0 CET}
-    {3352669200 7200 1 CEST}
-    {3370813200 3600 0 CET}
-    {3384118800 7200 1 CEST}
-    {3402867600 3600 0 CET}
-    {3415568400 7200 1 CEST}
-    {3434317200 3600 0 CET}
-    {3447018000 7200 1 CEST}
-    {3465766800 3600 0 CET}
-    {3479072400 7200 1 CEST}
-    {3497216400 3600 0 CET}
-    {3510522000 7200 1 CEST}
-    {3528666000 3600 0 CET}
-    {3541971600 7200 1 CEST}
-    {3560115600 3600 0 CET}
-    {3573421200 7200 1 CEST}
-    {3592170000 3600 0 CET}
-    {3604870800 7200 1 CEST}
-    {3623619600 3600 0 CET}
-    {3636320400 7200 1 CEST}
-    {3655069200 3600 0 CET}
-    {3668374800 7200 1 CEST}
-    {3686518800 3600 0 CET}
-    {3699824400 7200 1 CEST}
-    {3717968400 3600 0 CET}
-    {3731274000 7200 1 CEST}
-    {3750022800 3600 0 CET}
-    {3762723600 7200 1 CEST}
-    {3781472400 3600 0 CET}
-    {3794173200 7200 1 CEST}
-    {3812922000 3600 0 CET}
-    {3825622800 7200 1 CEST}
-    {3844371600 3600 0 CET}
-    {3857677200 7200 1 CEST}
-    {3875821200 3600 0 CET}
-    {3889126800 7200 1 CEST}
-    {3907270800 3600 0 CET}
-    {3920576400 7200 1 CEST}
-    {3939325200 3600 0 CET}
-    {3952026000 7200 1 CEST}
-    {3970774800 3600 0 CET}
-    {3983475600 7200 1 CEST}
-    {4002224400 3600 0 CET}
-    {4015530000 7200 1 CEST}
-    {4033674000 3600 0 CET}
-    {4046979600 7200 1 CEST}
-    {4065123600 3600 0 CET}
-    {4078429200 7200 1 CEST}
-    {4096573200 3600 0 CET}
+if {![info exists TZData(Europe/Berlin)]} {
+    LoadTimeZoneFile Europe/Berlin
 }
+set TZData(:Europe/Oslo) $TZData(:Europe/Berlin)
diff --git a/library/tzdata/Europe/Simferopol b/library/tzdata/Europe/Simferopol
index e296862..4a5a77f 100644
--- a/library/tzdata/Europe/Simferopol
+++ b/library/tzdata/Europe/Simferopol
@@ -38,11 +38,11 @@ set TZData(:Europe/Simferopol) {
     {749001600 7200 0 EET}
     {764726400 10800 1 EEST}
     {767743200 14400 0 MSD}
-    {780436800 10800 0 MSK}
-    {796165200 14400 1 MSD}
-    {811886400 10800 0 MSK}
+    {780447600 10800 0 MSK}
+    {796172400 14400 1 MSD}
+    {811897200 10800 0 MSK}
     {828219600 14400 1 MSD}
-    {852066000 10800 0 MSK}
+    {846374400 10800 0 MSK}
     {859683600 10800 0 EEST}
     {877827600 7200 0 EET}
     {891133200 10800 1 EEST}
diff --git a/library/tzdata/Europe/Stockholm b/library/tzdata/Europe/Stockholm
index b74d327..6b5c55a 100644
--- a/library/tzdata/Europe/Stockholm
+++ b/library/tzdata/Europe/Stockholm
@@ -1,250 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Europe/Stockholm) {
-    {-9223372036854775808 4332 0 LMT}
-    {-2871681132 3614 0 SET}
-    {-2208992414 3600 0 CET}
-    {-1692496800 7200 1 CEST}
-    {-1680483600 3600 0 CET}
-    {315529200 3600 0 CET}
-    {323830800 7200 1 CEST}
-    {338950800 3600 0 CET}
-    {354675600 7200 1 CEST}
-    {370400400 3600 0 CET}
-    {386125200 7200 1 CEST}
-    {401850000 3600 0 CET}
-    {417574800 7200 1 CEST}
-    {433299600 3600 0 CET}
-    {449024400 7200 1 CEST}
-    {465354000 3600 0 CET}
-    {481078800 7200 1 CEST}
-    {496803600 3600 0 CET}
-    {512528400 7200 1 CEST}
-    {528253200 3600 0 CET}
-    {543978000 7200 1 CEST}
-    {559702800 3600 0 CET}
-    {575427600 7200 1 CEST}
-    {591152400 3600 0 CET}
-    {606877200 7200 1 CEST}
-    {622602000 3600 0 CET}
-    {638326800 7200 1 CEST}
-    {654656400 3600 0 CET}
-    {670381200 7200 1 CEST}
-    {686106000 3600 0 CET}
-    {701830800 7200 1 CEST}
-    {717555600 3600 0 CET}
-    {733280400 7200 1 CEST}
-    {749005200 3600 0 CET}
-    {764730000 7200 1 CEST}
-    {780454800 3600 0 CET}
-    {796179600 7200 1 CEST}
-    {811904400 3600 0 CET}
-    {828234000 7200 1 CEST}
-    {846378000 3600 0 CET}
-    {859683600 7200 1 CEST}
-    {877827600 3600 0 CET}
-    {891133200 7200 1 CEST}
-    {909277200 3600 0 CET}
-    {922582800 7200 1 CEST}
-    {941331600 3600 0 CET}
-    {954032400 7200 1 CEST}
-    {972781200 3600 0 CET}
-    {985482000 7200 1 CEST}
-    {1004230800 3600 0 CET}
-    {1017536400 7200 1 CEST}
-    {1035680400 3600 0 CET}
-    {1048986000 7200 1 CEST}
-    {1067130000 3600 0 CET}
-    {1080435600 7200 1 CEST}
-    {1099184400 3600 0 CET}
-    {1111885200 7200 1 CEST}
-    {1130634000 3600 0 CET}
-    {1143334800 7200 1 CEST}
-    {1162083600 3600 0 CET}
-    {1174784400 7200 1 CEST}
-    {1193533200 3600 0 CET}
-    {1206838800 7200 1 CEST}
-    {1224982800 3600 0 CET}
-    {1238288400 7200 1 CEST}
-    {1256432400 3600 0 CET}
-    {1269738000 7200 1 CEST}
-    {1288486800 3600 0 CET}
-    {1301187600 7200 1 CEST}
-    {1319936400 3600 0 CET}
-    {1332637200 7200 1 CEST}
-    {1351386000 3600 0 CET}
-    {1364691600 7200 1 CEST}
-    {1382835600 3600 0 CET}
-    {1396141200 7200 1 CEST}
-    {1414285200 3600 0 CET}
-    {1427590800 7200 1 CEST}
-    {1445734800 3600 0 CET}
-    {1459040400 7200 1 CEST}
-    {1477789200 3600 0 CET}
-    {1490490000 7200 1 CEST}
-    {1509238800 3600 0 CET}
-    {1521939600 7200 1 CEST}
-    {1540688400 3600 0 CET}
-    {1553994000 7200 1 CEST}
-    {1572138000 3600 0 CET}
-    {1585443600 7200 1 CEST}
-    {1603587600 3600 0 CET}
-    {1616893200 7200 1 CEST}
-    {1635642000 3600 0 CET}
-    {1648342800 7200 1 CEST}
-    {1667091600 3600 0 CET}
-    {1679792400 7200 1 CEST}
-    {1698541200 3600 0 CET}
-    {1711846800 7200 1 CEST}
-    {1729990800 3600 0 CET}
-    {1743296400 7200 1 CEST}
-    {1761440400 3600 0 CET}
-    {1774746000 7200 1 CEST}
-    {1792890000 3600 0 CET}
-    {1806195600 7200 1 CEST}
-    {1824944400 3600 0 CET}
-    {1837645200 7200 1 CEST}
-    {1856394000 3600 0 CET}
-    {1869094800 7200 1 CEST}
-    {1887843600 3600 0 CET}
-    {1901149200 7200 1 CEST}
-    {1919293200 3600 0 CET}
-    {1932598800 7200 1 CEST}
-    {1950742800 3600 0 CET}
-    {1964048400 7200 1 CEST}
-    {1982797200 3600 0 CET}
-    {1995498000 7200 1 CEST}
-    {2014246800 3600 0 CET}
-    {2026947600 7200 1 CEST}
-    {2045696400 3600 0 CET}
-    {2058397200 7200 1 CEST}
-    {2077146000 3600 0 CET}
-    {2090451600 7200 1 CEST}
-    {2108595600 3600 0 CET}
-    {2121901200 7200 1 CEST}
-    {2140045200 3600 0 CET}
-    {2153350800 7200 1 CEST}
-    {2172099600 3600 0 CET}
-    {2184800400 7200 1 CEST}
-    {2203549200 3600 0 CET}
-    {2216250000 7200 1 CEST}
-    {2234998800 3600 0 CET}
-    {2248304400 7200 1 CEST}
-    {2266448400 3600 0 CET}
-    {2279754000 7200 1 CEST}
-    {2297898000 3600 0 CET}
-    {2311203600 7200 1 CEST}
-    {2329347600 3600 0 CET}
-    {2342653200 7200 1 CEST}
-    {2361402000 3600 0 CET}
-    {2374102800 7200 1 CEST}
-    {2392851600 3600 0 CET}
-    {2405552400 7200 1 CEST}
-    {2424301200 3600 0 CET}
-    {2437606800 7200 1 CEST}
-    {2455750800 3600 0 CET}
-    {2469056400 7200 1 CEST}
-    {2487200400 3600 0 CET}
-    {2500506000 7200 1 CEST}
-    {2519254800 3600 0 CET}
-    {2531955600 7200 1 CEST}
-    {2550704400 3600 0 CET}
-    {2563405200 7200 1 CEST}
-    {2582154000 3600 0 CET}
-    {2595459600 7200 1 CEST}
-    {2613603600 3600 0 CET}
-    {2626909200 7200 1 CEST}
-    {2645053200 3600 0 CET}
-    {2658358800 7200 1 CEST}
-    {2676502800 3600 0 CET}
-    {2689808400 7200 1 CEST}
-    {2708557200 3600 0 CET}
-    {2721258000 7200 1 CEST}
-    {2740006800 3600 0 CET}
-    {2752707600 7200 1 CEST}
-    {2771456400 3600 0 CET}
-    {2784762000 7200 1 CEST}
-    {2802906000 3600 0 CET}
-    {2816211600 7200 1 CEST}
-    {2834355600 3600 0 CET}
-    {2847661200 7200 1 CEST}
-    {2866410000 3600 0 CET}
-    {2879110800 7200 1 CEST}
-    {2897859600 3600 0 CET}
-    {2910560400 7200 1 CEST}
-    {2929309200 3600 0 CET}
-    {2942010000 7200 1 CEST}
-    {2960758800 3600 0 CET}
-    {2974064400 7200 1 CEST}
-    {2992208400 3600 0 CET}
-    {3005514000 7200 1 CEST}
-    {3023658000 3600 0 CET}
-    {3036963600 7200 1 CEST}
-    {3055712400 3600 0 CET}
-    {3068413200 7200 1 CEST}
-    {3087162000 3600 0 CET}
-    {3099862800 7200 1 CEST}
-    {3118611600 3600 0 CET}
-    {3131917200 7200 1 CEST}
-    {3150061200 3600 0 CET}
-    {3163366800 7200 1 CEST}
-    {3181510800 3600 0 CET}
-    {3194816400 7200 1 CEST}
-    {3212960400 3600 0 CET}
-    {3226266000 7200 1 CEST}
-    {3245014800 3600 0 CET}
-    {3257715600 7200 1 CEST}
-    {3276464400 3600 0 CET}
-    {3289165200 7200 1 CEST}
-    {3307914000 3600 0 CET}
-    {3321219600 7200 1 CEST}
-    {3339363600 3600 0 CET}
-    {3352669200 7200 1 CEST}
-    {3370813200 3600 0 CET}
-    {3384118800 7200 1 CEST}
-    {3402867600 3600 0 CET}
-    {3415568400 7200 1 CEST}
-    {3434317200 3600 0 CET}
-    {3447018000 7200 1 CEST}
-    {3465766800 3600 0 CET}
-    {3479072400 7200 1 CEST}
-    {3497216400 3600 0 CET}
-    {3510522000 7200 1 CEST}
-    {3528666000 3600 0 CET}
-    {3541971600 7200 1 CEST}
-    {3560115600 3600 0 CET}
-    {3573421200 7200 1 CEST}
-    {3592170000 3600 0 CET}
-    {3604870800 7200 1 CEST}
-    {3623619600 3600 0 CET}
-    {3636320400 7200 1 CEST}
-    {3655069200 3600 0 CET}
-    {3668374800 7200 1 CEST}
-    {3686518800 3600 0 CET}
-    {3699824400 7200 1 CEST}
-    {3717968400 3600 0 CET}
-    {3731274000 7200 1 CEST}
-    {3750022800 3600 0 CET}
-    {3762723600 7200 1 CEST}
-    {3781472400 3600 0 CET}
-    {3794173200 7200 1 CEST}
-    {3812922000 3600 0 CET}
-    {3825622800 7200 1 CEST}
-    {3844371600 3600 0 CET}
-    {3857677200 7200 1 CEST}
-    {3875821200 3600 0 CET}
-    {3889126800 7200 1 CEST}
-    {3907270800 3600 0 CET}
-    {3920576400 7200 1 CEST}
-    {3939325200 3600 0 CET}
-    {3952026000 7200 1 CEST}
-    {3970774800 3600 0 CET}
-    {3983475600 7200 1 CEST}
-    {4002224400 3600 0 CET}
-    {4015530000 7200 1 CEST}
-    {4033674000 3600 0 CET}
-    {4046979600 7200 1 CEST}
-    {4065123600 3600 0 CET}
-    {4078429200 7200 1 CEST}
-    {4096573200 3600 0 CET}
+if {![info exists TZData(Europe/Berlin)]} {
+    LoadTimeZoneFile Europe/Berlin
 }
+set TZData(:Europe/Stockholm) $TZData(:Europe/Berlin)
diff --git a/library/tzdata/Iceland b/library/tzdata/Iceland
index eb3f3eb..3e7cd0c 100644
--- a/library/tzdata/Iceland
+++ b/library/tzdata/Iceland
@@ -1,5 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-if {![info exists TZData(Atlantic/Reykjavik)]} {
-    LoadTimeZoneFile Atlantic/Reykjavik
+if {![info exists TZData(Africa/Abidjan)]} {
+    LoadTimeZoneFile Africa/Abidjan
 }
-set TZData(:Iceland) $TZData(:Atlantic/Reykjavik)
+set TZData(:Iceland) $TZData(:Africa/Abidjan)
diff --git a/library/tzdata/Indian/Christmas b/library/tzdata/Indian/Christmas
index 76f8cbe..dea9f90 100644
--- a/library/tzdata/Indian/Christmas
+++ b/library/tzdata/Indian/Christmas
@@ -1,6 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Indian/Christmas) {
-    {-9223372036854775808 25372 0 LMT}
-    {-2364102172 25200 0 +07}
+if {![info exists TZData(Asia/Bangkok)]} {
+    LoadTimeZoneFile Asia/Bangkok
 }
+set TZData(:Indian/Christmas) $TZData(:Asia/Bangkok)
diff --git a/library/tzdata/Indian/Cocos b/library/tzdata/Indian/Cocos
index 833eb20..cb474c9 100644
--- a/library/tzdata/Indian/Cocos
+++ b/library/tzdata/Indian/Cocos
@@ -1,6 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Indian/Cocos) {
-    {-9223372036854775808 23260 0 LMT}
-    {-2209012060 23400 0 +0630}
+if {![info exists TZData(Asia/Yangon)]} {
+    LoadTimeZoneFile Asia/Yangon
 }
+set TZData(:Indian/Cocos) $TZData(:Asia/Yangon)
diff --git a/library/tzdata/Indian/Kerguelen b/library/tzdata/Indian/Kerguelen
index 93f2d94..b3cbeee 100644
--- a/library/tzdata/Indian/Kerguelen
+++ b/library/tzdata/Indian/Kerguelen
@@ -1,6 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Indian/Kerguelen) {
-    {-9223372036854775808 0 0 -00}
-    {-631152000 18000 0 +05}
+if {![info exists TZData(Indian/Maldives)]} {
+    LoadTimeZoneFile Indian/Maldives
 }
+set TZData(:Indian/Kerguelen) $TZData(:Indian/Maldives)
diff --git a/library/tzdata/Indian/Mahe b/library/tzdata/Indian/Mahe
index dcafc36..3c728d2 100644
--- a/library/tzdata/Indian/Mahe
+++ b/library/tzdata/Indian/Mahe
@@ -1,6 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Indian/Mahe) {
-    {-9223372036854775808 13308 0 LMT}
-    {-1988163708 14400 0 +04}
+if {![info exists TZData(Asia/Dubai)]} {
+    LoadTimeZoneFile Asia/Dubai
 }
+set TZData(:Indian/Mahe) $TZData(:Asia/Dubai)
diff --git a/library/tzdata/Indian/Reunion b/library/tzdata/Indian/Reunion
index aa78dec..14f2320 100644
--- a/library/tzdata/Indian/Reunion
+++ b/library/tzdata/Indian/Reunion
@@ -1,6 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Indian/Reunion) {
-    {-9223372036854775808 13312 0 LMT}
-    {-1848886912 14400 0 +04}
+if {![info exists TZData(Asia/Dubai)]} {
+    LoadTimeZoneFile Asia/Dubai
 }
+set TZData(:Indian/Reunion) $TZData(:Asia/Dubai)
diff --git a/library/tzdata/Pacific/Chuuk b/library/tzdata/Pacific/Chuuk
index ea1cba2..5e2960c 100644
--- a/library/tzdata/Pacific/Chuuk
+++ b/library/tzdata/Pacific/Chuuk
@@ -1,11 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Pacific/Chuuk) {
-    {-9223372036854775808 -49972 0 LMT}
-    {-3944628428 36428 0 LMT}
-    {-2177489228 36000 0 +10}
-    {-1743674400 32400 0 +09}
-    {-1606813200 36000 0 +10}
-    {-907408800 32400 0 +09}
-    {-770634000 36000 0 +10}
+if {![info exists TZData(Pacific/Port_Moresby)]} {
+    LoadTimeZoneFile Pacific/Port_Moresby
 }
+set TZData(:Pacific/Chuuk) $TZData(:Pacific/Port_Moresby)
diff --git a/library/tzdata/Pacific/Easter b/library/tzdata/Pacific/Easter
index 7a8d525..97e1f4f 100644
--- a/library/tzdata/Pacific/Easter
+++ b/library/tzdata/Pacific/Easter
@@ -110,7 +110,7 @@ set TZData(:Pacific/Easter) {
     {1617505200 -21600 0 -06}
     {1630814400 -18000 1 -06}
     {1648954800 -21600 0 -06}
-    {1662264000 -18000 1 -06}
+    {1662868800 -18000 1 -06}
     {1680404400 -21600 0 -06}
     {1693713600 -18000 1 -06}
     {1712458800 -21600 0 -06}
diff --git a/library/tzdata/Pacific/Funafuti b/library/tzdata/Pacific/Funafuti
index d806525..d932469 100644
--- a/library/tzdata/Pacific/Funafuti
+++ b/library/tzdata/Pacific/Funafuti
@@ -1,6 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Pacific/Funafuti) {
-    {-9223372036854775808 43012 0 LMT}
-    {-2177495812 43200 0 +12}
+if {![info exists TZData(Pacific/Tarawa)]} {
+    LoadTimeZoneFile Pacific/Tarawa
 }
+set TZData(:Pacific/Funafuti) $TZData(:Pacific/Tarawa)
diff --git a/library/tzdata/Pacific/Majuro b/library/tzdata/Pacific/Majuro
index a263a62..b30f494 100644
--- a/library/tzdata/Pacific/Majuro
+++ b/library/tzdata/Pacific/Majuro
@@ -1,12 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Pacific/Majuro) {
-    {-9223372036854775808 41088 0 LMT}
-    {-2177493888 39600 0 +11}
-    {-1743678000 32400 0 +09}
-    {-1606813200 39600 0 +11}
-    {-1041418800 36000 0 +10}
-    {-907408800 32400 0 +09}
-    {-818067600 39600 0 +11}
-    {-7988400 43200 0 +12}
+if {![info exists TZData(Pacific/Tarawa)]} {
+    LoadTimeZoneFile Pacific/Tarawa
 }
+set TZData(:Pacific/Majuro) $TZData(:Pacific/Tarawa)
diff --git a/library/tzdata/Pacific/Pohnpei b/library/tzdata/Pacific/Pohnpei
index 7d0adf3..a8d9779 100644
--- a/library/tzdata/Pacific/Pohnpei
+++ b/library/tzdata/Pacific/Pohnpei
@@ -1,12 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Pacific/Pohnpei) {
-    {-9223372036854775808 -48428 0 LMT}
-    {-3944629972 37972 0 LMT}
-    {-2177490772 39600 0 +11}
-    {-1743678000 32400 0 +09}
-    {-1606813200 39600 0 +11}
-    {-1041418800 36000 0 +10}
-    {-907408800 32400 0 +09}
-    {-770634000 39600 0 +11}
+if {![info exists TZData(Pacific/Guadalcanal)]} {
+    LoadTimeZoneFile Pacific/Guadalcanal
 }
+set TZData(:Pacific/Pohnpei) $TZData(:Pacific/Guadalcanal)
diff --git a/library/tzdata/Pacific/Ponape b/library/tzdata/Pacific/Ponape
index 89644f7..1211f14 100644
--- a/library/tzdata/Pacific/Ponape
+++ b/library/tzdata/Pacific/Ponape
@@ -1,5 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-if {![info exists TZData(Pacific/Pohnpei)]} {
-    LoadTimeZoneFile Pacific/Pohnpei
+if {![info exists TZData(Pacific/Guadalcanal)]} {
+    LoadTimeZoneFile Pacific/Guadalcanal
 }
-set TZData(:Pacific/Ponape) $TZData(:Pacific/Pohnpei)
+set TZData(:Pacific/Ponape) $TZData(:Pacific/Guadalcanal)
diff --git a/library/tzdata/Pacific/Truk b/library/tzdata/Pacific/Truk
index c9b1894..7ddbad7 100644
--- a/library/tzdata/Pacific/Truk
+++ b/library/tzdata/Pacific/Truk
@@ -1,5 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-if {![info exists TZData(Pacific/Chuuk)]} {
-    LoadTimeZoneFile Pacific/Chuuk
+if {![info exists TZData(Pacific/Port_Moresby)]} {
+    LoadTimeZoneFile Pacific/Port_Moresby
 }
-set TZData(:Pacific/Truk) $TZData(:Pacific/Chuuk)
+set TZData(:Pacific/Truk) $TZData(:Pacific/Port_Moresby)
diff --git a/library/tzdata/Pacific/Wake b/library/tzdata/Pacific/Wake
index 67eab37..945a863 100644
--- a/library/tzdata/Pacific/Wake
+++ b/library/tzdata/Pacific/Wake
@@ -1,6 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Pacific/Wake) {
-    {-9223372036854775808 39988 0 LMT}
-    {-2177492788 43200 0 +12}
+if {![info exists TZData(Pacific/Tarawa)]} {
+    LoadTimeZoneFile Pacific/Tarawa
 }
+set TZData(:Pacific/Wake) $TZData(:Pacific/Tarawa)
diff --git a/library/tzdata/Pacific/Wallis b/library/tzdata/Pacific/Wallis
index 152e6af..92748f4 100644
--- a/library/tzdata/Pacific/Wallis
+++ b/library/tzdata/Pacific/Wallis
@@ -1,6 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-
-set TZData(:Pacific/Wallis) {
-    {-9223372036854775808 44120 0 LMT}
-    {-2177496920 43200 0 +12}
+if {![info exists TZData(Pacific/Tarawa)]} {
+    LoadTimeZoneFile Pacific/Tarawa
 }
+set TZData(:Pacific/Wallis) $TZData(:Pacific/Tarawa)
diff --git a/library/tzdata/Pacific/Yap b/library/tzdata/Pacific/Yap
index 4931030..f0b6ae7 100644
--- a/library/tzdata/Pacific/Yap
+++ b/library/tzdata/Pacific/Yap
@@ -1,5 +1,5 @@
 # created by tools/tclZIC.tcl - do not edit
-if {![info exists TZData(Pacific/Chuuk)]} {
-    LoadTimeZoneFile Pacific/Chuuk
+if {![info exists TZData(Pacific/Port_Moresby)]} {
+    LoadTimeZoneFile Pacific/Port_Moresby
 }
-set TZData(:Pacific/Yap) $TZData(:Pacific/Chuuk)
+set TZData(:Pacific/Yap) $TZData(:Pacific/Port_Moresby)
diff --git a/library/tzdata/US/Pacific-New b/library/tzdata/US/Pacific-New
deleted file mode 100644
index 2eb30f8..0000000
--- a/library/tzdata/US/Pacific-New
+++ /dev/null
@@ -1,5 +0,0 @@
-# created by tools/tclZIC.tcl - do not edit
-if {![info exists TZData(America/Los_Angeles)]} {
-    LoadTimeZoneFile America/Los_Angeles
-}
-set TZData(:US/Pacific-New) $TZData(:America/Los_Angeles)
diff --git a/tests-perf/comparePerf.tcl b/tests-perf/comparePerf.tcl
new file mode 100644
index 0000000..f35da21
--- /dev/null
+++ b/tests-perf/comparePerf.tcl
@@ -0,0 +1,371 @@
+#!/usr/bin/tclsh
+# ------------------------------------------------------------------------
+#
+# comparePerf.tcl --
+#
+#  Script to compare performance data from multiple runs.
+#
+# ------------------------------------------------------------------------
+#
+# See the file "license.terms" for information on usage and redistribution
+# of this file.
+#
+# Usage:
+#   tclsh comparePerf.tcl [--regexp RE] [--ratio time|rate] [--combine] [--base BASELABEL] PERFFILE ...
+#
+# The test data from each input file is tabulated so as to compare the results
+# of test runs. If a PERFFILE does not exist, it is retried by adding the
+# .perf extension. If the --regexp is specified, only test results whose
+# id matches RE are examined.
+#
+# If the --combine option is specified, results of test sets with the same
+# label are combined and averaged in the output.
+#
+# If the --base option is specified, the BASELABEL is used as the label to use
+# the base timing. Otherwise, the label of the first data file is used.
+#
+# If --ratio option is "time" the ratio of test timing vs base test timing
+# is shown. If "rate" (default) the inverse is shown.
+#
+# If --no-header is specified, the header describing test configuration is
+# not output.
+#
+# The format of input files is as follows:
+#
+# Each line must begin with one of the characters below followed by a space
+# followed by a string whose semantics depend on the initial character.
+# E - Full path to the Tcl executable that was used to generate the file
+# V - The Tcl patchlevel of the implementation
+# D - A description for the test run for human consumption
+# L - A label used to identify run environment. The --combine option will
+#     average all measuremets that have the same label. An input file without
+#     a label is treated as having a unique label and not combined with any other.
+# P - A test measurement (see below)
+# R - The number of runs made for the each test
+# # - A comment, may be an arbitrary string. Usually included in performance
+#     data to describe the test. This is silently ignored
+#
+# Any lines not matching one of the above are ignored with a warning to stderr.
+#
+# A line beginning with the "P" marker is a test measurement. The first word
+# following is a floating point number representing the test runtime.
+# The remaining line (after trimming of whitespace) is the id of the test.
+# Test generators are encouraged to make the id a well-defined machine-parseable
+# as well human readable description of the test. The id must not appear more
+# than once. An example test measurement line:
+# P    2.32280 linsert in unshared L[10000] 1 elems 10000 times at 0 (var)
+# Note here the iteration count is not present.
+#
+
+namespace eval perf::compare {
+    # List of dictionaries, one per input file
+    variable PerfData
+}
+
+proc perf::compare::warn {message} {
+    puts stderr "Warning: $message"
+}
+proc perf::compare::print {text} {
+    puts stdout $text
+}
+proc perf::compare::slurp {testrun_path} {
+    variable PerfData
+
+    set runtimes [dict create]
+
+    set path [file normalize $testrun_path]
+    set fd [open $path]
+    array set header {}
+    while {[gets $fd line] >= 0} {
+        set line [regsub -all {\s+} [string trim $line] " "]
+        switch -glob -- $line {
+            "#*" {
+                # Skip comments
+            }
+            "R *" -
+            "L *" -
+            "D *" -
+            "V *" -
+            "T *" -
+            "E *" {
+                set marker [lindex $line 0]
+                if {[info exists header($marker)]} {
+                    warn "Ignoring $marker record (duplicate): \"$line\""
+                }
+                set header($marker) [string range $line 2 end]
+            }
+            "P *" {
+                if {[scan $line "P %f %n" runtime id_start] == 2} {
+                    set id [string range $line $id_start end]
+                    if {[dict exists $runtimes $id]} {
+                        warn "Ignoring duplicate test id \"$id\""
+                    } else {
+                        dict set runtimes $id $runtime
+                    }
+                } else {
+                    warn "Invalid test result line format: \"$line\""
+                }
+            }
+            default {
+                puts stderr "Warning: ignoring unrecognized line \"$line\""
+            }
+        }
+    }
+    close $fd
+
+    set result [dict create Input $path Runtimes $runtimes]
+    foreach {c k} {
+        L Label
+        V Version
+        E Executable
+        D Description
+    } {
+        if {[info exists header($c)]} {
+            dict set result $k $header($c)
+        }
+    }
+
+    return $result
+}
+
+proc perf::compare::burp {test_sets} {
+    variable Options
+
+    # Print the key for each test run
+    set header "           "
+    set separator "           "
+    foreach test_set $test_sets {
+        set test_set_key "\[[incr test_set_num]\]"
+        if {! $Options(--no-header)} {
+            print "$test_set_key"
+            foreach k {Label Executable Version Input Description} {
+                if {[dict exists $test_set $k]} {
+                    print "$k: [dict get $test_set $k]"
+                }
+            }
+        }
+        append header $test_set_key $separator
+        set separator "                 "; # Expand because later columns have ratio
+    }
+    set header [string trimright $header]
+
+    if {! $Options(--no-header)} {
+        print ""
+        if {$Options(--ratio) eq "rate"} {
+            set ratio_description "ratio of baseline to the measurement (higher is faster)."
+        } else {
+            set ratio_description "ratio of measurement to the baseline (lower is faster)."
+        }
+        print "The first column \[1\] is the baseline measurement."
+        print "Subsequent columns are pairs of the additional measurement and "
+        print $ratio_description
+        print ""
+    }
+
+    # Print the actual test run data
+
+    print $header
+    set test_sets [lassign $test_sets base_set]
+    set fmt {%#10.5f}
+    set fmt_ratio {%-6.2f}
+    foreach {id base_runtime} [dict get $base_set Runtimes] {
+        if {[info exists Options(--regexp)]} {
+            if {![regexp $Options(--regexp) $id]} {
+                continue
+            }
+        }
+        if {$Options(--print-test-number)} {
+            set line "[format %-4s [incr counter].]"
+        } else {
+            set line ""
+        }
+        append line [format $fmt $base_runtime]
+        foreach test_set $test_sets {
+            if {[dict exists $test_set Runtimes $id]} {
+                set runtime [dict get $test_set Runtimes $id]
+                if {$Options(--ratio) eq "time"} {
+                    if {$base_runtime != 0} {
+                        set ratio [format $fmt_ratio [expr {$runtime/$base_runtime}]]
+                    } else {
+                        if {$runtime == 0} {
+                            set ratio "NaN   "
+                        } else {
+                            set ratio "Inf   "
+                        }
+                    }
+                } else {
+                    if {$runtime != 0} {
+                        set ratio [format $fmt_ratio [expr {$base_runtime/$runtime}]]
+                    } else {
+                        if {$base_runtime == 0} {
+                            set ratio "NaN   "
+                        } else {
+                            set ratio "Inf   "
+                        }
+                    }
+                }
+                append line "|" [format $fmt $runtime] "|" $ratio
+            } else {
+                append line [string repeat { } 11]
+            }
+        }
+        append line "|" $id
+        print $line
+    }
+}
+
+proc perf::compare::chew {test_sets} {
+    variable Options
+
+    # Combine test sets that have the same label, averaging the values
+    set unlabeled_sets {}
+    array set labeled_sets {}
+
+    foreach test_set $test_sets {
+        # If there is no label, treat as independent set
+        if {![dict exists $test_set Label]} {
+            lappend unlabeled_sets $test_set
+        } else {
+            lappend labeled_sets([dict get $test_set Label]) $test_set
+        }
+    }
+
+    foreach label [array names labeled_sets] {
+        set combined_set [lindex $labeled_sets($label) 0]
+        set runtimes [dict get $combined_set Runtimes]
+        foreach test_set [lrange $labeled_sets($label) 1 end] {
+            dict for {id timing} [dict get $test_set Runtimes] {
+                dict lappend runtimes $id $timing
+            }
+        }
+        dict for {id timings} $runtimes {
+            set total [tcl::mathop::+ {*}$timings]
+            dict set runtimes $id [expr {$total/[llength $timings]}]
+        }
+        dict set combined_set Runtimes $runtimes
+        set labeled_sets($label) $combined_set
+    }
+
+    # Choose the "base" test set
+    if {![info exists Options(--base)]} {
+        set first_set [lindex $test_sets 0]
+        if {[dict exists $first_set Label]} {
+            # Use label of first as the base
+            set Options(--base) [dict get $first_set Label]
+        }
+    }
+
+    if {[info exists Options(--base)] && $Options(--base) ne ""} {
+        lappend combined_sets $labeled_sets($Options(--base));# Will error if no such
+        unset labeled_sets($Options(--base))
+    } else {
+        lappend combined_sets [lindex $unlabeled_sets 0]
+        set unlabeled_sets [lrange $unlabeled_sets 1 end]
+    }
+    foreach label [array names labeled_sets] {
+        lappend combined_sets $labeled_sets($label)
+    }
+    lappend combined_sets {*}$unlabeled_sets
+
+    return $combined_sets
+}
+
+proc perf::compare::setup {argv} {
+    variable Options
+
+    array set Options {
+        --ratio rate
+        --combine 0
+        --print-test-number 0
+        --no-header 0
+    }
+    while {[llength $argv]} {
+        set argv [lassign $argv arg]
+        switch -glob -- $arg {
+            -r -
+            --regexp {
+                if {[llength $argv] == 0} {
+                    error "Missing value for option $arg"
+                }
+                set argv [lassign $argv val]
+                set Options(--regexp) $val
+            }
+            --ratio {
+                if {[llength $argv] == 0} {
+                    error "Missing value for option $arg"
+                }
+                set argv [lassign $argv val]
+                if {$val ni {time rate}} {
+                    error "Value for option $arg must be either \"time\" or \"rate\""
+                }
+                set Options(--ratio) $val
+            }
+            --print-test-number -
+            --combine -
+            --no-header {
+                set Options($arg) 1
+            }
+            --base {
+                if {[llength $argv] == 0} {
+                    error "Missing value for option $arg"
+                }
+                set argv [lassign $argv val]
+                set Options($arg) $val
+            }
+            -- {
+                # Remaining will be passed back to the caller
+                break
+            }
+            --* {
+                error "Unknown option $arg"
+            }
+            -* {
+                error "Unknown option -[lindex $arg 0]"
+            }
+            default {
+                # Remaining will be passed back to the caller
+                set argv [linsert $argv 0 $arg]
+                break;
+            }
+        }
+    }
+
+    set paths {}
+    foreach path $argv {
+        set path [file join $path]; # Convert from native else glob fails
+        if {[file isfile $path]} {
+            lappend paths $path
+            continue
+        }
+        if {[file isfile $path.perf]} {
+            lappend paths $path.perf
+            continue
+        }
+        lappend paths {*}[glob -nocomplain $path]
+    }
+    return $paths
+}
+proc perf::compare::main {} {
+    variable Options
+
+    set paths [setup $::argv]
+    if {[llength $paths] == 0} {
+        error "No test data files specified."
+    }
+    set test_data [list ]
+    set seen [dict create]
+    foreach path $paths {
+        if {![dict exists $seen $path]} {
+            lappend test_data [slurp $path]
+            dict set seen $path ""
+        }
+    }
+
+    if {$Options(--combine)} {
+        set test_data [chew $test_data]
+    }
+
+    burp $test_data
+}
+
+perf::compare::main
diff --git a/tests-perf/listPerf.tcl b/tests-perf/listPerf.tcl
new file mode 100644
index 0000000..17f22e9
--- /dev/null
+++ b/tests-perf/listPerf.tcl
@@ -0,0 +1,1290 @@
+#!/usr/bin/tclsh
+# ------------------------------------------------------------------------
+#
+# listPerf.tcl --
+#
+#  This file provides performance tests for list operations.
+#
+# ------------------------------------------------------------------------
+#
+# See the file "license.terms" for information on usage and redistribution
+# of this file.
+#
+# Note: this file does not use the test-performance.tcl framework as we want
+# more direct control over timerate options.
+
+catch {package require twapi}
+
+namespace eval perf::list {
+    variable perfScript [file normalize [info script]]
+
+    # Test for each of these lengths
+    variable Lengths {10 100 1000 10000}
+
+    variable RunTimes
+    set RunTimes(command) 0.0
+    set RunTimes(total) 0.0
+
+    variable Options
+    array set Options {
+        --print-comments   0
+        --print-iterations 0
+    }
+
+    # Procs used for calibrating overhead
+    proc proc2args {a b} {}
+    proc proc3args {a b c} {}
+
+    proc print {s} {
+        puts $s
+    }
+    proc print_usage {} {
+        puts stderr "Usage: [file tail [info nameofexecutable]] $::argv0 \[options\] \[command ...\]"
+        puts stderr "\t--description DESC\tHuman readable description of test run"
+        puts stderr "\t--label LABEL\tA label used to identify test environment"
+        puts stderr "\t--print-comments\tPrint comment for each test"
+        puts stderr "\t--print-iterations\tPrint number of iterations run for each test"
+    }
+
+    proc setup {argv} {
+        variable Options
+        variable Lengths
+
+        while {[llength $argv]} {
+            set argv [lassign $argv arg]
+            switch -glob -- $arg {
+                --print-comments -
+                --print-iterations {
+                    set Options($arg) 1
+                }
+                --label -
+                --description {
+                    if {[llength $argv] == 0} {
+                        error "Missing value for option $arg"
+                    }
+                    set argv [lassign $argv val]
+                    set Options($arg) $val
+                }
+                --lengths {
+                    if {[llength $argv] == 0} {
+                        error "Missing value for option $arg"
+                    }
+                    set argv [lassign $argv val]
+                    set Lengths $val
+                }
+                -- {
+                    # Remaining will be passed back to the caller
+                    break
+                }
+                --* {
+                    error "Unknown option $arg"
+                }
+                default {
+                    # Remaining will be passed back to the caller
+                    set argv [linsert $argv 0 $arg]
+                    break;
+                }
+            }
+        }
+
+        return $argv
+    }
+    proc format_timings {us iters} {
+        variable Options
+        if {!$Options(--print-iterations)} {
+            return "[format {%#10.4f} $us]"
+        }
+        return "[format {%#10.4f} $us] [format {%8d} $iters]"
+    }
+    proc measure {id script args} {
+        variable NullOverhead
+        variable RunTimes
+        variable Options
+
+        set opts(-overhead) ""
+        set opts(-runs) 5
+        while {[llength $args]} {
+            set args [lassign $args opt]
+            if {[llength $args] == 0} {
+                error "No argument supplied for $opt option. Test: $id"
+            }
+            set args [lassign $args val]
+            switch $opt {
+                -setup -
+                -cleanup -
+                -overhead -
+                -time -
+                -runs -
+                -reps {
+                    set opts($opt) $val
+                }
+                default {
+                    error "Unknown option $opt. Test: $id"
+                }
+            }
+        }
+
+        set timerate_args {}
+        if {[info exists opts(-time)]} {
+            lappend timerate_args $opts(-time)
+        }
+        if {[info exists opts(-reps)]} {
+            if {[info exists opts(-time)]} {
+                set timerate_args [list $opts(-time) $opts(-reps)]
+            } else {
+                # Force the default for first time option
+                set timerate_args [list 1000 $opts(-reps)]
+            }
+        } elseif {[info exists opts(-time)]} {
+            set timerate_args [list $opts(-time)]
+        }
+        if {[info exists opts(-setup)]} {
+            uplevel 1 $opts(-setup)
+        }
+        # Cache the empty overhead to prevent unnecessary delays. Note if you modify
+        # to cache other scripts, the cache key must be AFTER substituting the
+        # overhead script in the caller's context.
+        if {$opts(-overhead) eq ""} {
+            if {![info exists NullOverhead]} {
+                set NullOverhead [lindex [timerate {}] 0]
+            }
+            set overhead_us $NullOverhead
+        } else {
+            # The overhead measurements might use setup so we need to setup
+            # first and then cleanup in preparation for setting up again for
+            # the script to be measured
+            if {[info exists opts(-setup)]} {
+                uplevel 1 $opts(-setup)
+            }
+            set overhead_us [lindex [uplevel 1 [list timerate $opts(-overhead)]] 0]
+            if {[info exists opts(-cleanup)]} {
+                uplevel 1 $opts(-cleanup)
+            }
+        }
+        set timings {}
+        for {set i 0} {$i < $opts(-runs)} {incr i} {
+            if {[info exists opts(-setup)]} {
+                uplevel 1 $opts(-setup)
+            }
+            lappend timings [uplevel 1 [list timerate -overhead $overhead_us $script {*}$timerate_args]]
+            if {[info exists opts(-cleanup)]} {
+                uplevel 1 $opts(-cleanup)
+            }
+        }
+        set timings [lsort -real -index 0 $timings]
+        if {$opts(-runs) > 15} {
+            set ignore [expr {$opts(-runs)/8}]
+        } elseif {$opts(-runs) >= 5} {
+            set ignore 2
+        } else {
+            set ignore 0
+        }
+        # Ignore highest and lowest
+        set timings [lrange $timings 0 end-$ignore]
+        # Average it out
+        set us 0
+        set iters 0
+        foreach timing $timings {
+            set us [expr {$us + [lindex $timing 0]}]
+            set iters [expr {$iters + [lindex $timing 2]}]
+        }
+        set us [expr {$us/[llength $timings]}]
+        set iters [expr {$iters/[llength $timings]}]
+
+        set RunTimes(command) [expr {$RunTimes(command) + $us}]
+        print "P [format_timings $us $iters] $id"
+    }
+    proc comment {args} {
+        variable Options
+        if {$Options(--print-comments)} {
+            print "# [join $args { }]"
+        }
+    }
+    proc spanned_list {len} {
+        # Note - for small len, this will not create a spanned list
+        set delta [expr {$len/8}]
+        return [lrange [lrepeat [expr {$len+(2*$delta)}] a] $delta [expr {$delta+$len-1}]]
+    }
+    proc print_separator {command} {
+        comment [string repeat = 80]
+        comment Command: $command
+    }
+
+    oo::class create ListPerf {
+        constructor {args} {
+            my variable Opts
+            # Note default Opts can be overridden in construct as well as in measure
+            set Opts [dict merge {
+                -setup {
+                    set L [lrepeat $len a]
+                    set Lspan [perf::list::spanned_list $len]
+                } -cleanup {
+                    unset -nocomplain L
+                    unset -nocomplain Lspan
+                    unset -nocomplain L2
+                }
+            } $args]
+        }
+        method measure {comment script locals args} {
+            my variable Opts
+            dict with locals {}
+            ::perf::list::measure $comment $script {*}[dict merge $Opts $args]
+        }
+        method option {opt val} {
+            my variable Opts
+            dict set Opts $opt $val
+        }
+        method option_unset {opt} {
+            my variable Opts
+            unset -nocomplain Opts($opt)
+        }
+    }
+
+    proc linsert_describe {share_mode len at num iters} {
+        return "linsert L\[$len\] $share_mode $num elems $iters times at $at"
+    }
+    proc linsert_perf {} {
+        variable Lengths
+
+        print_separator linsert
+
+        ListPerf create perf -overhead {set L {}} -time 1000
+
+        # Note: Const indices take different path through bytecode than variable
+        # indices hence separate cases below
+
+
+        # Var case
+        foreach share_mode {shared unshared} {
+            set idx 0
+            if {$share_mode eq "shared"} {
+                comment == Insert into empty lists
+                comment Insert one element into empty list
+                measure [linsert_describe shared 0 "0 (var)" 1 1] {linsert $L $idx ""} -setup {set idx 0; set L {}}
+            } else {
+                comment == Insert into empty lists
+                comment Insert one element into empty list
+                measure [linsert_describe unshared 0 "0 (var)" 1 1] {linsert {} $idx ""} -setup {set idx 0}
+            }
+            foreach idx_str [list 0 1 mid end-1 end] {
+                foreach len $Lengths {
+                    if {$idx_str eq "mid"} {
+                        set idx [expr {$len/2}]
+                    } else {
+                        set idx $idx_str
+                    }
+                    # perf option -reps $reps
+                    set reps 1000
+                    if {$share_mode eq "shared"} {
+                        comment Insert once to shared list with variable index
+                        perf measure [linsert_describe shared $len "$idx (var)" 1 1] \
+                            {linsert $L $idx x} [list len $len idx $idx] -overhead {} -reps 100000
+
+                        comment Insert multiple times to shared list with variable index
+                        perf measure [linsert_describe shared $len "$idx (var)" 1 $reps] {
+                            set L [linsert $L $idx X]
+                        } [list len $len idx $idx] -reps $reps
+
+                        comment Insert multiple items multiple times to shared list with variable index
+                        perf measure [linsert_describe shared $len "$idx (var)" 5 $reps] {
+                            set L [linsert $L $idx X X X X X]
+                        } [list len $len idx $idx] -reps $reps
+                    } else {
+                        # NOTE : the Insert once case is left out for unshared lists
+                        # because it requires re-init on every iteration resulting
+                        # in a lot of measurement noise
+                        comment Insert multiple times to unshared list with variable index
+                        perf measure [linsert_describe unshared $len "$idx (var)" 1 $reps] {
+                            set L [linsert $L[set L {}] $idx X]
+                        } [list len $len idx $idx] -reps $reps
+                        comment Insert multiple items multiple times to unshared list with variable index
+                        perf measure [linsert_describe unshared $len "$idx (var)" 5 $reps] {
+                            set L [linsert $L[set L {}] $idx X X X X X]
+                        } [list len $len idx $idx] -reps $reps
+                    }
+                }
+            }
+        }
+
+        # Const index
+        foreach share_mode {shared unshared} {
+            if {$share_mode eq "shared"} {
+                comment == Insert into empty lists
+                comment Insert one element into empty list
+                measure [linsert_describe shared 0 "0 (const)" 1 1] {linsert $L 0 ""} -setup {set L {}}
+            } else {
+                comment == Insert into empty lists
+                comment Insert one element into empty list
+                measure [linsert_describe unshared 0 "0 (const)" 1 1] {linsert {} 0 ""}
+            }
+            foreach idx_str [list 0 1 mid end end-1] {
+                foreach len $Lengths {
+                    # Note end, end-1 explicitly calculated as otherwise they
+                    # are not treated as const
+                    if {$idx_str eq "mid"} {
+                        set idx [expr {$len/2}]
+                    } elseif {$idx_str eq "end"} {
+                        set idx [expr {$len-1}]
+                    } elseif {$idx_str eq "end-1"} {
+                        set idx [expr {$len-2}]
+                    } else {
+                        set idx $idx_str
+                    }
+                    #perf option -reps $reps
+                    set reps 100
+                    if {$share_mode eq "shared"} {
+                        comment Insert once to shared list with const index
+                        perf measure [linsert_describe shared $len "$idx (const)" 1 1] \
+                            "linsert \$L $idx x" [list len $len] -overhead {} -reps 10000
+
+                        comment Insert multiple times to shared list with const index
+                        perf measure [linsert_describe shared $len "$idx (const)" 1 $reps] \
+                            "set L \[linsert \$L $idx X\]" [list len $len] -reps $reps
+
+                        comment Insert multiple items multiple times to shared list with const index
+                        perf measure [linsert_describe shared $len "$idx (const)" 5 $reps] \
+                            "set L \[linsert \$L $idx X X X X X\]" [list len $len] -reps $reps
+                    } else {
+                        comment Insert multiple times to unshared list with const index
+                        perf measure [linsert_describe unshared $len "$idx (const)" 1 $reps] \
+                            "set L \[linsert \$L\[set L {}\] $idx X]" [list len $len] -reps $reps
+
+                        comment Insert multiple items multiple times to unshared list with const index
+                        perf measure [linsert_describe unshared $len "$idx (const)" 5 $reps] \
+                            "set L \[linsert \$L\[set L {}\] $idx X X X X X]" [list len $len] -reps $reps
+                    }
+                }
+            }
+        }
+
+        # Note: no span tests because the inserts above will themselves create
+        # spanned lists
+
+        perf destroy
+    }
+
+    proc list_describe {len text} {
+        return "list L\[$len\] $text"
+    }
+    proc list_perf {} {
+        variable Lengths
+
+        print_separator list
+
+        ListPerf create perf
+        foreach len $Lengths {
+            set s [join [lrepeat $len x]]
+            comment Create a list from a string
+            perf measure [list_describe $len "from a string"] {list $s} [list s $s len $len]
+        }
+        foreach len $Lengths {
+            comment Create a list from expansion - single list (special optimal case)
+            perf measure [list_describe $len "from a {*}list"] {list {*}$L} [list len $len]
+            comment Create a list from two lists - real test of expansion speed
+            perf measure [list_describe $len "from a {*}list {*}list"] {list {*}$L {*}$L} [list len [expr {$len/2}]]
+        }
+    }
+
+    proc lappend_describe {share_mode len num iters} {
+        return "lappend L\[$len\] $share_mode $num elems $iters times"
+    }
+    proc lappend_perf {} {
+        variable Lengths
+
+        print_separator lappend
+
+        ListPerf create perf -setup {set L [lrepeat [expr {$len/4}] x]}
+
+        # Shared
+        foreach len $Lengths {
+            comment Append to a shared list variable multiple times
+            perf measure [lappend_describe shared [expr {$len/2}] 1 $len] {
+                set L2 $L; # Make shared
+                lappend L x
+            } [list len $len] -reps $len -overhead {set L2 $L}
+        }
+
+        # Unshared
+        foreach len $Lengths {
+            comment Append to a unshared list variable multiple times
+            perf measure [lappend_describe unshared [expr {$len/2}] 1 $len] {
+                lappend L x
+            } [list len $len] -reps $len
+        }
+
+        # Span
+        foreach len $Lengths {
+            comment Append to a unshared-span list variable multiple times
+            perf measure [lappend_describe unshared-span [expr {$len/2}] 1 $len] {
+                lappend Lspan x
+            } [list len $len] -reps $len
+        }
+
+        perf destroy
+    }
+
+    proc lpop_describe {share_mode len at reps} {
+        return "lpop L\[$len\] $share_mode at $at $reps times"
+    }
+    proc lpop_perf {} {
+        variable Lengths
+
+        print_separator lpop
+
+        ListPerf create perf
+
+        # Shared
+        perf option -overhead {set L2 $L}
+        foreach len $Lengths {
+            set reps [expr {($len >= 1000 ? ($len/2) : $len) - 2}]
+            foreach idx {0 1 end-1 end}  {
+                comment Pop element at position $idx from a shared list variable
+                perf measure [lpop_describe shared $len $idx $reps] {
+                    set L2 $L
+                    lpop L $idx
+                } [list len $len idx $idx] -reps $reps
+            }
+        }
+
+        # Unshared
+        perf option -overhead {}
+        foreach len $Lengths {
+            set reps [expr {($len >= 1000 ? ($len/2) : $len) - 2}]
+            foreach idx {0 1 end-1 end}  {
+                comment Pop element at position $idx from an unshared list variable
+                perf measure [lpop_describe unshared $len $idx $reps] {
+                    lpop L $idx
+                } [list len $len idx $idx] -reps $reps
+            }
+        }
+
+        perf destroy
+
+        # Nested
+        ListPerf create perf -setup {
+            set L [lrepeat $len [list a b]]
+        }
+
+        # Shared, nested index
+        perf option -overhead {set L2 $L; set L L2}
+        foreach len $Lengths {
+            set reps [expr {($len >= 1000 ? ($len/2) : $len) - 2}]
+            foreach idx {0 1 end-1 end}  {
+                perf measure [lpop_describe shared $len "{$idx 0}" $reps] {
+                    set L2 $L
+                    lpop L $idx 0
+                    set L $L2
+                } [list len $len idx $idx] -reps $reps
+            }
+        }
+
+        # TODO - Nested Unshared
+        # Not sure how to measure performance. When unshared there is no copy
+        # so deleting a nested index repeatedly is not feasible
+
+        perf destroy
+    }
+
+    proc lassign_describe {share_mode len num reps} {
+        return "lassign L\[$len\] $share_mode $num elems $reps times"
+    }
+    proc lassign_perf {} {
+        variable Lengths
+
+        print_separator lassign
+
+        ListPerf create perf
+
+        foreach share_mode {shared unshared} {
+            foreach len $Lengths {
+                if {$share_mode eq "shared"} {
+                    set reps 1000
+                    comment Reflexive lassign - shared
+                    perf measure [lassign_describe shared $len 1 $reps] {
+                        set L2 $L
+                        set L2 [lassign $L2 v]
+                    } [list len $len] -overhead {set L2 $L} -reps $reps
+
+                    comment Reflexive lassign - shared, multiple
+                    perf measure [lassign_describe shared $len 5 $reps] {
+                        set L2 $L
+                        set L2 [lassign $L2 a b c d e]
+                    } [list len $len] -overhead {set L2 $L} -reps $reps
+                } else {
+                    set reps [expr {($len >= 1000 ? ($len/2) : $len) - 2}]
+                    comment Reflexive lassign - unshared
+                    perf measure [lassign_describe unshared $len 1 $reps] {
+                        set L [lassign $L v]
+                    } [list len $len] -reps $reps
+                }
+            }
+        }
+        perf destroy
+    }
+
+    proc lrepeat_describe {len num} {
+        return "lrepeat L\[$len\] $num elems at a time"
+    }
+    proc lrepeat_perf {} {
+        variable Lengths
+
+        print_separator lrepeat
+
+        ListPerf create perf -reps 100000
+        foreach len $Lengths {
+            comment Generate a list from a single repeated element
+            perf measure [lrepeat_describe $len 1] {
+                lrepeat $len a
+            } [list len $len]
+
+            comment Generate a list from multiple repeated elements
+            perf measure [lrepeat_describe $len 5] {
+                lrepeat $len a b c d e
+            } [list len $len]
+        }
+
+        perf destroy
+    }
+
+    proc lreverse_describe {share_mode len} {
+        return "lreverse L\[$len\] $share_mode"
+    }
+    proc lreverse_perf {} {
+        variable Lengths
+
+        print_separator lreverse
+
+        ListPerf create perf -reps 10000
+
+        foreach share_mode {shared unshared} {
+            foreach len $Lengths {
+                if {$share_mode eq "shared"} {
+                    comment Reverse a shared list
+                    perf measure [lreverse_describe shared $len] {
+                        lreverse $L
+                    } [list len $len]
+
+                    if {$len > 100} {
+                        comment Reverse a shared-span list
+                        perf measure [lreverse_describe shared-span $len] {
+                            lreverse $Lspan
+                        } [list len $len]
+                    }
+                } else {
+                    comment Reverse a unshared list
+                    perf measure [lreverse_describe unshared $len] {
+                        set L [lreverse $L[set L {}]]
+                    } [list len $len] -overhead {set L $L; set L {}}
+
+                    if {$len >= 100} {
+                        comment Reverse a unshared-span list
+                        perf measure [lreverse_describe unshared-span $len] {
+                            set Lspan [lreverse $Lspan[set Lspan {}]]
+                        } [list len $len] -overhead {set Lspan $Lspan; set Lspan {}}
+                    }
+                }
+            }
+        }
+
+        perf destroy
+    }
+
+    proc llength_describe {share_mode len} {
+        return "llength L\[$len\] $share_mode"
+    }
+    proc llength_perf {} {
+        variable Lengths
+
+        print_separator llength
+
+        ListPerf create perf -reps 100000
+
+        foreach len $Lengths {
+            comment Length of a list
+            perf measure [llength_describe shared $len] {
+                llength $L
+            } [list len $len]
+
+            if {$len >= 100} {
+                comment Length of a span list
+                perf measure [llength_describe shared-span $len] {
+                    llength $Lspan
+                } [list len $len]
+            }
+        }
+
+        perf destroy
+    }
+
+    proc lindex_describe {share_mode len at} {
+        return "lindex L\[$len\] $share_mode at $at"
+    }
+    proc lindex_perf {} {
+        variable Lengths
+
+        print_separator lindex
+
+        ListPerf create perf -reps 100000
+
+        foreach len $Lengths {
+            comment Index into a list
+            set idx [expr {$len/2}]
+            perf measure [lindex_describe shared $len $idx] {
+                lindex $L $idx
+            } [list len $len idx $idx]
+
+            if {$len >= 100} {
+                comment Index into a span list
+                perf measure [lindex_describe shared-span $len $idx] {
+                    lindex $Lspan $idx
+                } [list len $len idx $idx]
+            }
+        }
+
+        perf destroy
+    }
+
+    proc lrange_describe {share_mode len range} {
+        return "lrange L\[$len\] $share_mode range $range"
+    }
+
+    proc lrange_perf {} {
+        variable Lengths
+
+        print_separator lrange
+
+        ListPerf create perf -time 1000 -reps 100000
+
+        foreach share_mode {shared unshared} {
+            foreach len $Lengths {
+                set eighth [expr {$len/8}]
+                set ranges [list \
+                                [list 0 0]  [list 0 end-1] \
+                                [list $eighth [expr {3*$eighth}]] \
+                                [list $eighth [expr {7*$eighth}]] \
+                                [list 1 end] [list end-1 end] \
+                               ]
+                foreach range $ranges {
+                    comment Range $range in $share_mode list of length $len
+                    if {$share_mode eq "shared"} {
+                        perf measure [lrange_describe shared $len $range] \
+                            "lrange \$L $range" [list len $len range $range]
+                    } else {
+                        perf measure [lrange_describe unshared $len $range] \
+                            "lrange \[lrepeat \$len\ a] $range" \
+                            [list len $len range $range] -overhead {lrepeat $len a}
+                    }
+                }
+
+                if {$len >= 100} {
+                    foreach range $ranges {
+                        comment Range $range in ${share_mode}-span list of length $len
+                        if {$share_mode eq "shared"} {
+                            perf measure [lrange_describe shared-span $len $range] \
+                                "lrange \$Lspan {*}$range" [list len $len range $range]
+                        } else {
+                            perf measure [lrange_describe unshared-span $len $range] \
+                                "lrange \[perf::list::spanned_list \$len\] $range" \
+                                [list len $len range $range] -overhead {perf::list::spanned_list $len}
+                        }
+                    }
+                }
+            }
+        }
+
+        perf destroy
+    }
+
+    proc lset_describe {share_mode len at} {
+        return "lset L\[$len\] $share_mode at $at"
+    }
+    proc lset_perf {} {
+        variable Lengths
+
+        print_separator lset
+
+        ListPerf create perf -reps 10000
+
+        # Shared
+        foreach share_mode {shared unshared} {
+            foreach len $Lengths {
+                foreach idx {0 1 end-1 end end+1}  {
+                    comment lset at position $idx in a $share_mode list variable
+                    if {$share_mode eq "shared"} {
+                        perf measure [lset_describe shared $len $idx] {
+                            set L2 $L
+                            lset L $idx X
+                        } [list len $len idx $idx] -overhead {set L2 $L}
+                    } else {
+                        perf measure [lset_describe unshared $len $idx] {
+                            lset L $idx X
+                        } [list len $len idx $idx]
+                    }
+                }
+            }
+        }
+
+        perf destroy
+
+        # Nested
+        ListPerf create perf -setup {
+            set L [lrepeat $len [list a b]]
+        }
+
+        foreach share_mode {shared unshared} {
+            foreach len $Lengths {
+                foreach idx {0 1 end-1 end}  {
+                    comment lset at position $idx in a $share_mode list variable
+                    if {$share_mode eq "shared"} {
+                        perf measure [lset_describe shared $len "{$idx 0}"] {
+                            set L2 $L
+                            lset L $idx 0 X
+                        } [list len $len idx $idx] -overhead {set L2 $L}
+                    } else {
+                        perf measure [lset_describe unshared $len "{$idx 0}"] {
+                            lset L $idx 0 {X Y}
+                        } [list len $len idx $idx]
+                    }
+                }
+            }
+        }
+
+        perf destroy
+    }
+
+    proc lremove_describe {share_mode len at nremoved} {
+        return "lremove L\[$len\] $share_mode $nremoved elements at $at"
+    }
+    proc lremove_perf {} {
+        variable Lengths
+
+        print_separator lremove
+
+        ListPerf create perf -reps 10000
+
+        foreach share_mode {shared unshared} {
+            foreach len $Lengths {
+                foreach idx [list 0 1 [expr {$len/2}] end-1 end] {
+                    if {$share_mode eq "shared"} {
+                        comment Remove one element from shared list
+                        perf measure [lremove_describe shared $len $idx 1] \
+                            {lremove $L $idx} [list len $len idx $idx]
+
+                    } else {
+                        comment Remove one element from unshared list
+                        set reps [expr {$len >= 1000 ? ($len/8) : ($len-2)}]
+                        perf measure [lremove_describe unshared $len $idx 1] \
+                            {set L [lremove $L[set L {}] $idx]} [list len $len idx $idx] \
+                            -overhead {set L $L; set L {}} -reps $reps
+                    }
+                }
+                if {$share_mode eq "shared"} {
+                    comment Remove multiple elements from shared list
+                    perf measure [lremove_describe shared $len [list 0 1 [expr {$len/2}] end-1 end] 5] {
+                        lremove $L 0 1 [expr {$len/2}] end-1 end
+                    } [list len $len]
+                }
+            }
+            # Span
+            foreach len $Lengths {
+                foreach idx [list 0 1 [expr {$len/2}] end-1 end] {
+                    if {$share_mode eq "shared"} {
+                        comment Remove one element from shared-span list
+                        perf measure [lremove_describe shared-span $len $idx 1] \
+                            {lremove $Lspan $idx} [list len $len idx $idx]
+                    } else {
+                        comment Remove one element from unshared-span list
+                        set reps [expr {$len >= 1000 ? ($len/8) : ($len-2)}]
+                        perf measure [lremove_describe unshared-span $len $idx 1] \
+                            {set Lspan [lremove $Lspan[set Lspan {}] $idx]} [list len $len idx $idx] \
+                            -overhead {set Lspan $Lspan; set Lspan {}} -reps $reps
+                    }
+                }
+                if {$share_mode eq "shared"} {
+                    comment Remove multiple elements from shared-span list
+                    perf measure [lremove_describe shared-span $len [list 0 1 [expr {$len/2}] end-1 end] 5] {
+                        lremove $Lspan 0 1 [expr {$len/2}] end-1 end
+                    } [list len $len]
+                }
+            }
+        }
+
+        perf destroy
+    }
+
+    proc lreplace_describe {share_mode len first last ninsert {times 1}} {
+        if {$last < $first} {
+            return "lreplace L\[$len\] $share_mode 0 ($first:$last) elems at $first with $ninsert elems $times times."
+        }
+        return "lreplace L\[$len\] $share_mode $first:$last with $ninsert elems $times times."
+    }
+    proc lreplace_perf {} {
+        variable Lengths
+
+        print_separator lreplace
+
+        set default_reps 10000
+        ListPerf create perf -reps $default_reps
+
+        foreach share_mode {shared unshared} {
+            # Insert only
+            foreach len $Lengths {
+                set reps [expr {$len <= 100 ? ($len-2) : ($len/8)}]
+                foreach first [list 0 1 [expr {$len/2}] end-1 end] {
+                    if {$share_mode eq "shared"} {
+                        comment Insert one to shared list
+                        perf measure [lreplace_describe shared $len $first -1 1] {
+                            lreplace $L $first -1 x
+                        } [list len $len first $first]
+
+                        comment Insert multiple to shared list
+                        perf measure [lreplace_describe shared $len $first -1 10] {
+                            lreplace $L $first -1 X X X X X X X X X X
+                        } [list len $len first $first]
+
+                        comment Insert one to shared list repeatedly
+                        perf measure [lreplace_describe shared $len $first -1 1 $reps] {
+                            set L [lreplace $L $first -1 x]
+                        } [list len $len first $first] -reps $reps
+
+                        comment Insert multiple to shared list repeatedly
+                        perf measure [lreplace_describe shared $len $first -1 10 $reps] {
+                            set L [lreplace $L $first -1 X X X X X X X X X X]
+                        } [list len $len first $first] -reps $reps
+
+                    } else {
+                        comment Insert one to unshared list
+                        perf measure [lreplace_describe unshared $len $first -1 1] {
+                            set L [lreplace $L[set L {}] $first -1 x]
+                        } [list len $len first $first] -overhead {
+                            set L $L; set L {}
+                        } -reps $reps
+
+                        comment Insert multiple to unshared list
+                        perf measure [lreplace_describe unshared $len $first -1 10] {
+                            set L [lreplace $L[set L {}] $first -1 X X X X X X X X X X]
+                        } [list len $len first $first] -overhead {
+                            set L $L; set L {}
+                        } -reps $reps
+                    }
+                }
+            }
+
+            # Delete only
+            foreach len $Lengths {
+                set reps [expr {$len <= 100 ? ($len-2) : ($len/8)}]
+                foreach first [list 0 1 [expr {$len/2}] end-1 end] {
+                    if {$share_mode eq "shared"} {
+                        comment Delete one from shared list
+                        perf measure [lreplace_describe shared $len $first $first 0] {
+                            lreplace $L $first $first
+                        } [list len $len first $first]
+                    } else {
+                        comment Delete one from unshared list
+                        perf measure [lreplace_describe unshared $len $first $first 0] {
+                            set L [lreplace $L[set L {}] $first $first x]
+                        } [list len $len first $first] -overhead {
+                            set L $L; set L {}
+                        } -reps $reps
+                    }
+                }
+            }
+
+            # Insert + delete
+            foreach len $Lengths {
+                set reps [expr {$len <= 100 ? ($len-2) : ($len/8)}]
+                foreach range [list {0 1} {1 2} {end-2 end-1} {end-1 end}] {
+                    lassign $range first last
+                    if {$share_mode eq "shared"} {
+                        comment Insertions more than deletions from shared list
+                        perf measure [lreplace_describe shared $len $first $last 3] {
+                            lreplace $L $first $last X Y Z
+                        } [list len $len first $first last $last]
+
+                        comment Insertions same as deletions from shared list
+                        perf measure [lreplace_describe shared $len $first $last 2] {
+                            lreplace $L $first $last X Y
+                        } [list len $len first $first last $last]
+
+                        comment Insertions fewer than deletions from shared list
+                        perf measure [lreplace_describe shared $len $first $last 1] {
+                            lreplace $L $first $last X
+                        } [list len $len first $first last $last]
+                    } else {
+                        comment Insertions more than deletions from unshared list
+                        perf measure [lreplace_describe unshared $len $first $last 3] {
+                            set L [lreplace $L[set L {}] $first $last X Y Z]
+                        } [list len $len first $first last $last] -overhead {
+                            set L $L; set L {}
+                        } -reps $reps
+
+                        comment Insertions same as deletions from unshared list
+                        perf measure [lreplace_describe unshared $len $first $last 2] {
+                            set L [lreplace $L[set L {}] $first $last X Y ]
+                        } [list len $len first $first last $last] -overhead {
+                            set L $L; set L {}
+                        } -reps $reps
+
+                        comment Insertions fewer than deletions from unshared list
+                        perf measure [lreplace_describe unshared $len $first $last 1] {
+                            set L [lreplace $L[set L {}] $first $last X]
+                        } [list len $len first $first last $last] -overhead {
+                            set L $L; set L {}
+                        } -reps $reps
+                    }
+                }
+            }
+            # Spanned Insert + delete
+            foreach len $Lengths {
+                set reps [expr {$len <= 100 ? ($len-2) : ($len/8)}]
+                foreach range [list {0 1} {1 2} {end-2 end-1} {end-1 end}] {
+                    lassign $range first last
+                    if {$share_mode eq "shared"} {
+                        comment Insertions more than deletions from shared-span list
+                        perf measure [lreplace_describe shared-span $len $first $last 3] {
+                            lreplace $Lspan $first $last X Y Z
+                        } [list len $len first $first last $last]
+
+                        comment Insertions same as deletions from shared-span list
+                        perf measure [lreplace_describe shared-span $len $first $last 2] {
+                            lreplace $Lspan $first $last X Y
+                        } [list len $len first $first last $last]
+
+                        comment Insertions fewer than deletions from shared-span list
+                        perf measure [lreplace_describe shared-span $len $first $last 1] {
+                            lreplace $Lspan $first $last X
+                        } [list len $len first $first last $last]
+                    } else {
+                        comment Insertions more than deletions from unshared-span list
+                        perf measure [lreplace_describe unshared-span $len $first $last 3] {
+                            set Lspan [lreplace $Lspan[set Lspan {}] $first $last X Y Z]
+                        } [list len $len first $first last $last] -overhead {
+                            set Lspan $Lspan; set Lspan {}
+                        } -reps $reps
+
+                        comment Insertions same as deletions from unshared-span list
+                        perf measure [lreplace_describe unshared-span $len $first $last 2] {
+                            set Lspan [lreplace $Lspan[set Lspan {}] $first $last X Y ]
+                        } [list len $len first $first last $last] -overhead {
+                            set Lspan $Lspan; set Lspan {}
+                        } -reps $reps
+
+                        comment Insertions fewer than deletions from unshared-span list
+                        perf measure [lreplace_describe unshared-span $len $first $last 1] {
+                            set Lspan [lreplace $Lspan[set Lspan {}] $first $last X]
+                        } [list len $len first $first last $last] -overhead {
+                            set Lspan $Lspan; set Lspan {}
+                        } -reps $reps
+                    }
+                }
+            }
+        }
+
+        perf destroy
+    }
+
+    proc split_describe {len} {
+        return "split L\[$len\]"
+    }
+    proc split_perf {} {
+        variable Lengths
+        print_separator split
+
+        ListPerf create perf -setup {set S [string repeat "x " $len]}
+        foreach len $Lengths {
+            comment Split a string
+            perf measure [split_describe $len] {
+                split $S " "
+            } [list len $len]
+        }
+    }
+
+    proc join_describe {share_mode len} {
+        return "join L\[$len\] $share_mode"
+    }
+    proc join_perf {} {
+        variable Lengths
+
+        print_separator join
+
+        ListPerf create perf -reps 10000
+        foreach len $Lengths {
+            comment Join a list
+            perf measure [join_describe shared $len] {
+                join $L
+            } [list len $len]
+        }
+        foreach len $Lengths {
+            comment Join a spanned list
+            perf measure [join_describe shared-span $len] {
+                join $Lspan
+            } [list len $len]
+        }
+        perf destroy
+    }
+
+    proc lsearch_describe {share_mode len} {
+        return "lsearch L\[$len\] $share_mode"
+    }
+    proc lsearch_perf {} {
+        variable Lengths
+
+        print_separator lsearch
+
+        ListPerf create perf -reps 100000
+        foreach len $Lengths {
+            comment Search a list
+            perf measure [lsearch_describe shared $len] {
+                lsearch $L needle
+            } [list len $len]
+        }
+        foreach len $Lengths {
+            comment Search a spanned list
+            perf measure [lsearch_describe shared-span $len] {
+                lsearch $Lspan needle
+            } [list len $len]
+        }
+        perf destroy
+    }
+
+    proc foreach_describe {share_mode len} {
+        return "foreach L\[$len\] $share_mode"
+    }
+    proc foreach_perf {} {
+        variable Lengths
+
+        print_separator foreach
+
+        ListPerf create perf -reps 10000
+        foreach len $Lengths {
+            comment Iterate through a list
+            perf measure [foreach_describe shared $len] {
+                foreach e $L {}
+            } [list len $len]
+        }
+        foreach len $Lengths {
+            comment Iterate a spanned list
+            perf measure [foreach_describe shared-span $len] {
+                foreach e $Lspan {}
+            } [list len $len]
+        }
+        perf destroy
+    }
+
+    proc lmap_describe {share_mode len} {
+        return "lmap L\[$len\] $share_mode"
+    }
+    proc lmap_perf {} {
+        variable Lengths
+
+        print_separator lmap
+
+        ListPerf create perf -reps 10000
+        foreach len $Lengths {
+            comment Iterate through a list
+            perf measure [lmap_describe shared $len] {
+                lmap e $L {}
+            } [list len $len]
+        }
+        foreach len $Lengths {
+            comment Iterate a spanned list
+            perf measure [lmap_describe shared-span $len] {
+                lmap e $Lspan {}
+            } [list len $len]
+        }
+        perf destroy
+    }
+
+    proc get_sort_sample {{spanned 0}} {
+        variable perfScript
+        variable sortSampleText
+
+        if {![info exists sortSampleText]} {
+            set fd [open $perfScript]
+            set sortSampleText [split [read $fd] ""]
+            close $fd
+        }
+        set sortSampleText [string range $sortSampleText 0 9999]
+
+        # NOTE: do NOT cache list result in a variable as we need it unshared
+        if {$spanned} {
+            return [lrange [split $sortSampleText ""] 1 end-1]
+        } else {
+            return [split $sortSampleText ""]
+        }
+    }
+    proc lsort_describe {share_mode len} {
+        return "lsort L\[$len] $share_mode"
+    }
+    proc lsort_perf {} {
+        print_separator lsort
+
+        ListPerf create perf -setup {}
+
+        comment Sort a shared list
+        perf measure [lsort_describe shared [llength [perf::list::get_sort_sample]]] {
+            lsort $L
+        } {} -setup {set L [perf::list::get_sort_sample]}
+
+        comment Sort a shared-span list
+        perf measure [lsort_describe shared-span [llength [perf::list::get_sort_sample 1]]] {
+            lsort $L
+        } {} -setup {set L [perf::list::get_sort_sample 1]}
+
+        comment Sort an unshared list
+        perf measure [lsort_describe unshared [llength [perf::list::get_sort_sample]]] {
+            lsort [perf::list::get_sort_sample]
+        } {} -overhead {perf::list::get_sort_sample}
+
+        comment Sort an unshared-span list
+        perf measure [lsort_describe unshared-span [llength [perf::list::get_sort_sample 1]]] {
+            lsort [perf::list::get_sort_sample 1]
+        } {} -overhead {perf::list::get_sort_sample 1}
+
+        perf destroy
+    }
+
+    proc concat_describe {canonicality len elemlen} {
+        return "concat L\[$len\] $canonicality with elements of length $elemlen"
+    }
+    proc concat_perf {} {
+        variable Lengths
+
+        print_separator concat
+
+        ListPerf create perf -reps 100000
+
+        foreach len $Lengths {
+            foreach elemlen {1 100} {
+                comment Pure lists (no string representation)
+                perf measure [concat_describe "pure lists" $len $elemlen] {
+                    concat $L $L
+                } [list len $len elemlen $elemlen] -setup {
+                    set L [lrepeat $len [string repeat a $elemlen]]
+                }
+
+                comment Canonical lists (with string representation)
+                perf measure [concat_describe "canonical lists" $len $elemlen] {
+                    concat $L $L
+                } [list len $len elemlen $elemlen] -setup {
+                    set L [lrepeat $len [string repeat a $elemlen]]
+                    append x x $L; # Generate string while keeping internal rep list
+                    unset x
+                }
+
+                comment Non-canonical lists
+                perf measure [concat_describe "non-canonical lists" $len $elemlen] {
+                    concat $L $L
+                } [list len $len elemlen $elemlen] -setup {
+                    set L [string repeat "[string repeat a $elemlen] " $len]
+                    llength $L
+                }
+            }
+        }
+
+        # Span version
+        foreach len $Lengths {
+            foreach elemlen {1 100} {
+                comment Pure span lists (no string representation)
+                perf measure [concat_describe "pure spanned lists" $len $elemlen] {
+                    concat $L $L
+                } [list len $len elemlen $elemlen] -setup {
+                    set L [lrange [lrepeat [expr {$len+2}] [string repeat a $elemlen]] 1 end-1]
+                }
+
+                comment Canonical span lists (with string representation)
+                perf measure [concat_describe "canonical spanned lists" $len $elemlen] {
+                    concat $L $L
+                } [list len $len elemlen $elemlen] -setup {
+                    set L [lrange [lrepeat [expr {$len+2}] [string repeat a $elemlen]] 1 end-1]
+                    append x x $L; # Generate string while keeping internal rep list
+                    unset x
+                }
+            }
+        }
+
+        perf destroy
+    }
+
+    proc test {} {
+        variable RunTimes
+        variable Options
+
+        set selections [perf::list::setup $::argv]
+        if {[llength $selections] == 0} {
+            set commands [info commands ::perf::list::*_perf]
+        } else {
+            set commands [lmap sel $selections {
+                if {$sel eq "help"} {
+                    print_usage
+                    continue
+                }
+                set cmd ::perf::list::${sel}_perf
+                if {$cmd ni [info commands ::perf::list::*_perf]} {
+                    puts stderr "Error: command $sel is not known or supported. Skipping."
+                    continue
+                }
+                set cmd
+            }]
+        }
+        comment Setting up
+        timerate -calibrate {}
+        if {[info exists Options(--label)]} {
+            print "L $Options(--label)"
+        }
+        print "V [info patchlevel]"
+        print "E [info nameofexecutable]"
+        if {[info exists Options(--description)]} {
+            print "D $Options(--description)"
+        }
+        set twapi_keys {-privatebytes -workingset -workingsetpeak}
+        if {[info commands ::twapi::get_process_memory_info] ne ""} {
+            set twapi_vm_pre [::twapi::get_process_memory_info]
+        }
+        foreach cmd [lsort -dictionary $commands] {
+            set RunTimes(command) 0.0
+            $cmd
+            set RunTimes(total) [expr {$RunTimes(total)+$RunTimes(command)}]
+            print "P [format_timings $RunTimes(command) 1] [string range $cmd 14 end-5] total run time"
+        }
+        # Print total runtime in same format as timerate output
+        print "P [format_timings $RunTimes(total) 1] Total run time"
+
+        if {[info exists twapi_vm_pre]} {
+            set twapi_vm_post [::twapi::get_process_memory_info]
+            set MB 1048576.0
+            foreach key $twapi_keys {
+                set pre [expr {[dict get $twapi_vm_pre $key]/$MB}]
+                set post [expr {[dict get $twapi_vm_post $key]/$MB}]
+                print "P [format_timings $pre 1] Memory (MB) $key pre-test"
+                print "P [format_timings $post 1] Memory (MB) $key post-test"
+                print "P [format_timings [expr {$post-$pre}] 1] Memory (MB) delta $key"
+            }
+        }
+        if {[info commands memory] ne ""} {
+            foreach line [split [memory info] \n] {
+                if {$line eq ""} continue
+                set line [split $line]
+                set val [expr {[lindex $line end]/1000.0}]
+                set line [string trim [join [lrange $line 0 end-1]]]
+                print "P [format_timings $val 1] memdbg $line (in thousands)"
+            }
+            print "# Allocations not freed on exit written to the lost-memory.tmp file."
+            print "# These will have to be manually compared."
+            # env TCL_FINALIZE_ON_EXIT must be set to 1 for this.
+            # DO NOT SET HERE - set ::env(TCL_FINALIZE_ON_EXIT) 1
+            # Must be set in environment before starting tclsh else bogus results
+            if {[info exists Options(--label)]} {
+                set dump_file list-memory-$Options(--label).memdmp
+            } else {
+                set dump_file list-memory-[pid].memdmp
+            }
+            memory onexit $dump_file
+        }
+    }
+}
+
+
+if {[info exists ::argv0] && [file tail $::argv0] eq [file tail [info script]]} {
+    ::perf::list::test
+}
diff --git a/tests/apply.test b/tests/apply.test
index a5f1f8f..24b27cc 100644
--- a/tests/apply.test
+++ b/tests/apply.test
@@ -261,7 +261,7 @@ test apply-9.1 {leaking internal rep} -setup {
 	lindex $lines 3 3
     }
     set lam [list {} {set a 1}]
-} -constraints memory -body {
+} -constraints {memory} -body {
     set end [getbytes]
     for {set i 0} {$i < 5} {incr i} {
 	::apply [lrange $lam 0 end]
diff --git a/tests/env.test b/tests/env.test
index 9eacd5d..dd88431 100644
--- a/tests/env.test
+++ b/tests/env.test
@@ -107,6 +107,7 @@ variable keep {
     CommonProgramFiles CommonProgramFiles(x86) ProgramFiles
     ProgramFiles(x86) CommonProgramW6432 ProgramW6432
     WINECONFIGDIR WINEDATADIR WINEDLLDIR0 WINEHOMEDIR PROCESSOR_ARCHITECTURE
+    USERPROFILE
 }
 
 variable printenvScript [makeFile [string map [list @keep@ [list $keep]] {
@@ -411,7 +412,7 @@ test env-7.3 {
       return [info exists ::env(test7_3)]
     }}
 } -cleanup cleanup1 -result 1
-
+
 test env-8.0 {
     memory usage - valgrind does not report reachable memory
 } -body {
@@ -421,6 +422,45 @@ test env-8.0 {
 } -result {i'm with dummy}
 
 
+test env-9.0 {
+    Initialization of HOME from HOMEDRIVE and HOMEPATH
+} -constraints win -setup {
+    setup1
+    unset -nocomplain ::env(HOME)
+    set ::env(HOMEDRIVE) X:
+    set ::env(HOMEPATH) \\home\\path
+} -cleanup {
+    cleanup1
+} -body {
+    set pipe [open |[list [interpreter]] r+]
+    puts $pipe {puts $::env(HOME); flush stdout; exit}
+    flush $pipe
+    set result [gets $pipe]
+    close $pipe
+    set result
+} -result {X:\home\path}
+
+test env-9.1 {
+    Initialization of HOME from USERPROFILE
+} -constraints win -setup {
+    setup1
+    unset -nocomplain ::env(HOME)
+    unset -nocomplain ::env(HOMEDRIVE)
+    unset -nocomplain ::env(HOMEPATH)
+} -cleanup {
+    cleanup1
+} -body {
+    set pipe [open |[list [interpreter]] r+]
+    puts $pipe {puts $::env(HOME); flush stdout; exit}
+    flush $pipe
+    set result [gets $pipe]
+    close $pipe
+    if {$result ne $::env(USERPROFILE)} {
+	list ERROR $result ne $::env(USERPROFILE)
+    }
+} -result {}
+
+
 
 # cleanup
 rename getenv {}
diff --git a/tests/http.test b/tests/http.test
index a6f1ce6..26ba710 100644
--- a/tests/http.test
+++ b/tests/http.test
@@ -17,20 +17,7 @@ if {"::tcltest" ni [namespace children]} {
 }
 package require tcltests
 
-if {[catch {package require http 2} version]} {
-    if {[info exists http2]} {
-	catch {puts "Cannot load http 2.* package"}
-	return
-    } else {
-	catch {puts "Running http 2.* tests in child interp"}
-	set interp [interp create http2]
-	$interp eval [list set http2 "running"]
-	$interp eval [list set argv $argv]
-	$interp eval [list source [info script]]
-	interp delete $interp
-	return
-    }
-}
+package require http 2.10
 
 proc bgerror {args} {
     global errorInfo
@@ -78,11 +65,31 @@ if {[catch {package present Thread}] == 0 && [file exists $httpdFile]} {
 	return
     }
 }
+
+if {![info exists ThreadLevel]} {
+    if {[catch {package require Thread}] == 0} {
+        set ValueRange {0 1 2}
+    } else {
+        set ValueRange {0 1}
+    }
+
+    # For each value of ThreadLevel, source this file recursively in the
+    # same interpreter.
+    foreach ThreadLevel $ValueRange {
+        source [info script]
+    }
+    catch {unset ThreadLevel}
+    catch {unset ValueRange}
+    return
+}
+
+catch {puts "==== Test with ThreadLevel $ThreadLevel ===="}
+http::config -threadlevel $ThreadLevel
 
 test http-1.1 {http::config} {
     http::config -useragent UserAgent
     http::config
-} [list -accept */* -cookiejar {} -pipeline 1 -postfresh 0 -proxyfilter http::ProxyRequired -proxyhost {} -proxyport {} -repost 0 -urlencoding utf-8 -useragent UserAgent -zip 1]
+} [list -accept */* -cookiejar {} -pipeline 1 -postfresh 0 -proxyfilter http::ProxyRequired -proxyhost {} -proxyport {} -repost 0 -threadlevel $ThreadLevel -urlencoding utf-8 -useragent UserAgent -zip 1]
 test http-1.2 {http::config} {
     http::config -proxyfilter
 } http::ProxyRequired
@@ -97,10 +104,10 @@ test http-1.4 {http::config} {
     set x [http::config]
     http::config {*}$savedconf
     set x
-} {-accept */* -cookiejar {} -pipeline 1 -postfresh 0 -proxyfilter myFilter -proxyhost nowhere.come -proxyport 8080 -repost 0 -urlencoding iso8859-1 -useragent {Tcl Test Suite} -zip 1}
+} [list -accept */* -cookiejar {} -pipeline 1 -postfresh 0 -proxyfilter myFilter -proxyhost nowhere.come -proxyport 8080 -repost 0 -threadlevel $ThreadLevel -urlencoding iso8859-1 -useragent {Tcl Test Suite} -zip 1]
 test http-1.5 {http::config} -returnCodes error -body {
     http::config -proxyhost {} -junk 8080
-} -result {Unknown option -junk, must be: -accept, -cookiejar, -pipeline, -postfresh, -proxyfilter, -proxyhost, -proxyport, -repost, -urlencoding, -useragent, -zip}
+} -result {Unknown option -junk, must be: -accept, -cookiejar, -pipeline, -postfresh, -proxyfilter, -proxyhost, -proxyport, -repost, -threadlevel, -urlencoding, -useragent, -zip}
 test http-1.6 {http::config} -setup {
     set oldenc [http::config -urlencoding]
 } -body {
@@ -139,9 +146,11 @@ test http-2.8 {http::CharsetToEncoding} {
 test http-3.1 {http::geturl} -returnCodes error -body {
     http::geturl -bogus flag
 } -result {Unknown option flag, can be: -binary, -blocksize, -channel, -command, -handler, -headers, -keepalive, -method, -myaddr, -progress, -protocol, -query, -queryblocksize, -querychannel, -queryprogress, -strict, -timeout, -type, -validate}
+
 test http-3.2 {http::geturl} -returnCodes error -body {
     http::geturl http:junk
 } -result {Unsupported URL: http:junk}
+
 set url //${::HOST}:$port
 set badurl //${::HOST}:[expr {$port+1}]
 test http-3.3 {http::geturl} -body {
@@ -153,6 +162,7 @@ test http-3.3 {http::geturl} -body {
 <h1>Hello, World!</h1>
 <h2>GET /</h2>
 </body></html>"
+
 set tail /a/b/c
 set url //${::HOST}:$port/a/b/c
 set fullurl HTTP://user:pass@${::HOST}:$port/a/b/c
@@ -162,6 +172,7 @@ set posturl //${::HOST}:$port/post
 set badposturl //${::HOST}:$port/droppost
 set authorityurl //${::HOST}:$port
 set ipv6url http://\[::1\]:$port/
+
 test http-3.4 {http::geturl} -body {
     set token [http::geturl $url]
     http::data $token
@@ -572,6 +583,7 @@ test http-4.10 {http::Event} -body {
 } -cleanup {
     http::cleanup $token
 } -result {111}
+
 # Timeout cases
 #	Short timeout to working server (the test server). This lets us try a
 #	reset during the connection.
@@ -582,6 +594,7 @@ test http-4.11 {http::Event} -body {
 } -cleanup {
     http::cleanup $token
 } -result {reset}
+
 #	Longer timeout with reset.
 test http-4.12 {http::Event} -body {
     set token [http::geturl $url/?timeout=10 -keepalive 0 -command \#]
@@ -590,6 +603,7 @@ test http-4.12 {http::Event} -body {
 } -cleanup {
     http::cleanup $token
 } -result {reset}
+
 #	Medium timeout to working server that waits even longer. The timeout
 #	hits while waiting for a reply.
 test http-4.13 {http::Event} -body {
@@ -599,6 +613,7 @@ test http-4.13 {http::Event} -body {
 } -cleanup {
     http::cleanup $token
 } -result {timeout}
+
 #	Longer timeout to good host, bad port, gets an error after the
 #	connection "completes" but the socket is bad.
 test http-4.14 {http::Event} -body {
@@ -611,17 +626,19 @@ test http-4.14 {http::Event} -body {
 } -cleanup {
     catch {http::cleanup $token}
 } -result {connect failed connection refused}
+
 # Bogus host
 test http-4.15 {http::Event} -body {
     # This test may fail if you use a proxy server. That is to be
     # expected and is not a problem with Tcl.
     set token [http::geturl //not_a_host.tcl.tk -timeout 3000 -command \#]
     http::wait $token
-    http::status $token
+    set result "[http::status $token] -- [lindex [http::error $token] 0]"
     # error codes vary among platforms.
 } -cleanup {
     catch {http::cleanup $token}
-} -returnCodes 1 -match glob -result "couldn't open socket*"
+} -match glob -result "error -- couldn't open socket*"
+
 test http-4.16 {Leak with Close vs Keepalive (bug [6ca52aec14]} -setup {
     proc list-difference {l1 l2} {
 	lmap item $l2 {if {$item in $l1} continue; set item}
diff --git a/tests/http11.test b/tests/http11.test
index 4f6fb92..346e334 100644
--- a/tests/http11.test
+++ b/tests/http11.test
@@ -12,7 +12,7 @@ if {"::tcltest" ni [namespace children]} {
     namespace import -force ::tcltest::*
 }
 
-package require http 2.9
+package require http 2.10
 
 # start the server
 variable httpd_output
@@ -87,6 +87,26 @@ proc check_crc {tok args} {
 }
 
 makeFile "<html><head><title>test</title></head><body><p>this is a test</p>\n[string repeat {<p>This is a tcl test file.</p>} 4192]\n</body></html>" testdoc.html
+
+if {![info exists ThreadLevel]} {
+    if {[catch {package require Thread}] == 0} {
+        set ValueRange {0 1 2}
+    } else {
+        set ValueRange {0 1}
+    }
+
+    # For each value of ThreadLevel, source this file recursively in the
+    # same interpreter.
+    foreach ThreadLevel $ValueRange {
+        source [info script]
+    }
+    catch {unset ThreadLevel}
+    catch {unset ValueRange}
+    return
+}
+
+catch {puts "==== Test with ThreadLevel $ThreadLevel ===="}
+http::config -threadlevel $ThreadLevel
 
 # -------------------------------------------------------------------------
 
diff --git a/tests/httpPipeline.test b/tests/httpPipeline.test
index 4e55a10..161519f 100644
--- a/tests/httpPipeline.test
+++ b/tests/httpPipeline.test
@@ -13,7 +13,31 @@ if {"::tcltest" ni [namespace children]} {
     namespace import -force ::tcltest::*
 }
 
-package require http 2.9
+package require http 2.10
+
+# ------------------------------------------------------------------------------
+# (0) Socket Creation in Thread, which triples the number of tests.
+# ------------------------------------------------------------------------------
+
+if {![info exists ThreadLevel]} {
+    if {[catch {package require Thread}] == 0} {
+        set ValueRange {0 1 2}
+    } else {
+        set ValueRange {0 1}
+    }
+
+    # For each value of ThreadLevel, source this file recursively in the
+    # same interpreter.
+    foreach ThreadLevel $ValueRange {
+        source [info script]
+    }
+    catch {unset ThreadLevel}
+    catch {unset ValueRange}
+    return
+}
+
+catch {puts "==== Test with ThreadLevel $ThreadLevel ===="}
+http::config -threadlevel $ThreadLevel
 
 set sourcedir [file normalize [file dirname [info script]]]
 source [file join $sourcedir httpTest.tcl]
diff --git a/tests/httpd b/tests/httpd
index 43e9372..a7b42a1 100644
--- a/tests/httpd
+++ b/tests/httpd
@@ -50,7 +50,7 @@ proc httpdAccept {newsock ipaddr port} {
     fconfigure $newsock -blocking 0 -translation {auto crlf}
     httpd_log $newsock Connect $ipaddr $port
     set data(ipaddr) $ipaddr
-    after 50 [list fileevent $newsock readable [list httpdRead $newsock]]
+    fileevent $newsock readable [list httpdRead $newsock]
 }
 
 # read data from a client request
@@ -69,6 +69,10 @@ proc httpdRead { sock } {
 		-> data(proto) data(url) data(query) data(httpversion)]} {
 	    set data(state) mime
 	    httpd_log $sock Query $line
+	    if {[regexp {(?:^|[\?&])delay=([^&]+)} $data(query) {} val]} {
+		fileevent $sock readable {}
+		after $val [list fileevent $sock readable [list httpdRead $sock]]
+	    }
 	} else {
 	    httpdError $sock 400
 	    httpd_log $sock Error "bad first line:$line"
diff --git a/tests/io.test b/tests/io.test
index 6314ace..b6c4fb5 100644
--- a/tests/io.test
+++ b/tests/io.test
@@ -8952,6 +8952,39 @@ test io-74.1 {[104f2885bb] improper cache validity check} -setup {
     removeFile io-74.1
 } -returnCodes error -match glob -result {can not find channel named "*"}
 
+# Note: the following tests are in preparation for TCL 9.0, where those should
+# result in an error result
+test io-75.1 {multibyte encoding error read results in raw bytes} -setup {
+	set fn [makeFile {} io-75.1]
+    set f [open $fn w+]
+    fconfigure $f -encoding binary
+	puts -nonewline $f "A\xC0\x40"
+	flush $f
+	seek $f 0
+	fconfigure $f -encoding utf-8 -buffering none
+} -body {
+	read $f
+} -cleanup {
+	close $f
+	removeFile io-75.1
+} -returnCodes ok -result "A\xC0\x40"
+# for TCL 9.0, the result is error
+
+test io-75.2 {unrepresentable character write passes and is replaced by ?} -setup {
+	set fn [makeFile {} io-75.2]
+    set f [open $fn w+]
+    fconfigure $f -encoding iso8859-1
+} -body {
+	# the following command gets in result error in TCL 9.0
+	puts -nonewline $f "A\u2022"
+	flush $f
+	seek $f 0
+	read $f
+} -cleanup {
+	close $f
+	removeFile io-75.2
+} -returnCodes ok -result "A?"
+
 # ### ### ### ######### ######### #########
 
 # cleanup
diff --git a/tests/listRep.test b/tests/listRep.test
new file mode 100644
index 0000000..7883a21
--- /dev/null
+++ b/tests/listRep.test
@@ -0,0 +1,2538 @@
+# This file contains tests that specifically exercise the internal representation
+# of a list.
+#
+# Copyright © 2022 Ashok P. Nadkarni
+#
+# See the file "license.terms" for information on usage and redistribution
+# of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+
+# Unlike the other files related to list commands which for the most part do
+# black box testing focusing on functionality, this file does more of white box
+# testing to exercise code paths that implement different list representations
+# (with spans, leading free space etc., shared/unshared etc.) In addition to
+# functional correctness, the tests also check for the expected internal
+# representation as that pertains to performance heuristics. Generally speaking,
+# combinations of the following need to be tested,
+# - free space in front, back, neither, both of list representation
+# - shared Tcl_Objs
+# - shared internal reps (independent of shared Tcl_Objs)
+# - byte-compiled vs non-compiled
+#
+# Being white box tests, they are sensitive to changes to further optimizations
+# and changes in heuristics. That cannot be helped.
+
+if {"::tcltest" ni [namespace children]} {
+    package require tcltest 2.5
+    namespace import -force ::tcltest::*
+}
+
+::tcltest::loadTestedCommands
+catch [list package require -exact tcl::test [info patchlevel]]
+
+testConstraint testlistrep [llength [info commands testlistrep]]
+
+proc describe {l args} {dict get [testlistrep describe $l] {*}$args}
+
+proc irange {first last} {
+    set l {}
+    while {$first <= $last} {
+        lappend l $first
+        incr first
+    }
+    return $l
+}
+proc leadSpace {l} {
+    # Returns the leading space in a list store
+    return [dict get [describe $l] store firstUsed]
+}
+proc tailSpace {l} {
+    # Returns the trailing space in a list store
+    array set rep [describe $l]
+    dict with rep(store) {
+        return [expr {$numAllocated - ($firstUsed + $numUsed)}]
+    }
+}
+proc allocated {l} {
+    # Returns the allocated space in a list store
+    return [dict get [describe $l] store numAllocated]
+}
+proc repStoreRefCount {l} {
+    # Returns the ref count for the list store
+    return [dict get [describe $l] store refCount]
+}
+proc validate {l} {
+    # Panics if internal listrep structures are not valid
+    testlistrep validate $l
+}
+proc leadSpaceMore {l} {
+    set leadSpace [leadSpace $l]
+    expr {$leadSpace > 0 && $leadSpace >= 2*[tailSpace $l]}
+}
+proc tailSpaceMore {l} {
+    set tailSpace [tailSpace $l]
+    expr {$tailSpace > 0 && $tailSpace >= 2*[leadSpace $l]}
+}
+proc spaceEqual {l} {
+    # 1 if lead and tail space shared (diff of 1 at most) and more than 0
+    set leadSpace [leadSpace $l]
+    set tailSpace [tailSpace $l]
+    if {$leadSpace == 0 && $tailSpace == 0} {
+        # At least one must be positive
+        return 0
+    }
+    set diff [expr {$leadSpace - $tailSpace}]
+    return [expr {$diff >= -1 && $diff <= 1}]
+}
+proc storeAddress {l} {
+    return [describe $l store memoryAddress]
+}
+proc sameStore {l1 l2} {
+    expr {[storeAddress $l1] == [storeAddress $l2]}
+}
+proc hasSpan {l args} {
+    # Returns 1 if list has a span. If args are specified, they are checked with
+    # span values (start and length)
+    array set rep [describe $l]
+    if {![info exists rep(span)]} {
+        return 0
+    }
+    if {[llength $args] == 0} {
+        return 1; # No need to check values
+    }
+    lassign $args start len
+    if {[dict get $rep(span) spanStart] == $start &&
+        [dict get $rep(span) spanLength] == $len} {
+        return 1
+    }
+    return 0
+}
+proc checkListrep {l listLen numAllocated leadSpace tailSpace {refCount 0}} {
+    # Checks if the internal representation of $l match
+    # passed arguments. Return "" if yes, else error messages.
+    array set rep [testlistrep describe $l]
+
+    set rep(leadSpace) [dict get $rep(store) firstUsed]
+    set rep(numAllocated) [dict get $rep(store) numAllocated]
+    set rep(tailSpace) [expr {
+                              $rep(numAllocated) - ($rep(leadSpace) + [dict get $rep(store) numUsed])
+                          }]
+    set rep(refCount) [dict get $rep(store) refCount]
+
+    if {[info exists rep(span)]} {
+        set rep(listLen) [dict get $rep(span) spanLength]
+    } else {
+        set rep(listLen) [dict get $rep(store) numUsed]
+    }
+
+    set errors [list]
+    foreach arg {listLen numAllocated leadSpace tailSpace} {
+        if {$rep($arg) != [set $arg]} {
+            lappend errors "$arg in list representation ($rep($arg)) is not expected value ([set $arg])."
+        }
+    }
+    # Check refCount only if caller has specified it as non-0
+    if {$refCount && $refCount != $rep(refCount)} {
+        lappend errors "refCount in list representation ($rep(refCount)) is not expected value ($refCount)."
+    }
+    return $errors
+}
+
+proc assertListrep {l listLen numAllocated leadSpace tailSpace {refCount 0}} {
+    # Like check_listrep but raises error
+    set errors [checkListrep $l $listLen $numAllocated $leadSpace $tailSpace $refCount]
+    if {[llength $errors]} {
+        error [join $errors \n]
+    }
+    return
+}
+
+# The default length should be large enough that doubling the allocation will
+# clearly distinguish free space allocation difference between front and back.
+# (difference in the two should at least be 2 else we cannot tell if front
+# or back was favored appropriately)
+proc freeSpaceNone {{len 8}} {return [testlistrep new $len 0 0]}
+proc freeSpaceLead {{len 8} {lead 3}} {return [testlistrep new $len $lead 0]}
+proc freeSpaceTail {{len 8} {tail 3}} {return [testlistrep new $len 0 $tail]}
+proc freeSpaceBoth {{len 8} {lead 3} {tail 3}} {
+    return [testlistrep new $len $lead $tail]
+}
+proc zombieSample {{len 1000} {leadzombies 100} {tailzombies 100}} {
+    # returns an unshared listrep with zombies in front and back
+
+    # don't combine freespacenone and lrange else zombies are freed
+    set l [freeSpaceNone [expr {$len+$leadzombies+$tailzombies}]]
+    return [lrange $l $leadzombies [expr {$leadzombies+$len-1}]]
+}
+
+# Just ensure above stubs return what's expected
+if {[testConstraint testlistrep]} {
+    assertListrep [freeSpaceNone] 8 8 0 0 1
+    assertListrep [freeSpaceLead] 8 11 3 0 1
+    assertListrep [freeSpaceTail] 8 11 0 3 1
+    assertListrep [freeSpaceBoth] 8 14 3 3 1
+    assertListrep [zombieSample] 1000 1200 0 0 1
+    if {![hasSpan [zombieSample]] || [dict get [testlistrep describe [zombieSample]] span spanStart] == 0} {
+        error "zombieSample span missing or span start is at 0."
+    }
+}
+
+# Define some variables for some indices because the Tcl compiler will do some
+# operations completely in byte code if indices are literals
+set zero 0
+set one 1
+set two 2
+set four 4
+set end end
+
+#
+# Test sets:
+# 1.* - unshared internal rep, no spans, with no free space
+# 2.* - shared internal rep, no spans, with no free space
+# 3.* - unshared internal rep, spanned
+# 4.* - shared internal rep, spanned
+# 5.* - shared Tcl_Obj
+# 6.* - lists with zombie Tcl_Obj's
+
+#
+# listrep-1.* tests all operate on unshared listreps with no free space
+
+test listrep-1.1 {
+    Inserts in front of unshared list with no free space should reallocate with
+    equal free space at front and back -- linsert version
+} -constraints testlistrep -body {
+    set l [linsert [freeSpaceNone] $zero 99]
+    validate $l
+    list $l [spaceEqual $l]
+} -result [list {99 0 1 2 3 4 5 6 7} 1]
+
+test listrep-1.1.1 {
+    Inserts in front of unshared list with no free space should reallocate with
+    equal free space at front and back -- lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceNone] $zero -1 99]
+    validate $l
+    list $l [spaceEqual $l]
+} -result [list {99 0 1 2 3 4 5 6 7} 1]
+
+test listrep-1.2 {
+    Inserts at back of unshared list with no free space should allocate all
+    space at back -- linsert version
+} -constraints testlistrep -body {
+    set l [linsert [freeSpaceNone] $end 99]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 2 3 4 5 6 7 99} 0 9]
+
+test listrep-1.2.1 {
+    Inserts at back of unshared list with no free space should allocate all
+    space at back -- lset version
+} -constraints testlistrep -body {
+    set l [freeSpaceNone]
+    lset l $end+1 99
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 2 3 4 5 6 7 99} 0 9]
+
+test listrep-1.2.2 {
+    Inserts at back of unshared list with no free space should allocate all
+    space at back -- lappend version
+} -constraints testlistrep -body {
+    set l [freeSpaceNone]
+    lappend l 99
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 2 3 4 5 6 7 99} 0 9]
+
+test listrep-1.3 {
+    Inserts in middle of unshared list with no free space should reallocate with
+    equal free space at front and back - linsert version
+} -constraints testlistrep -body {
+    set l [linsert [freeSpaceNone] $four 99]
+    validate $l
+    list $l [spaceEqual $l]
+} -result [list {0 1 2 3 99 4 5 6 7} 1]
+
+test listrep-1.3.1 {
+    Inserts in middle of unshared list with no free space should reallocate with
+    equal free space at front and back - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceNone] $four $four-1 99]
+    validate $l
+    list $l [spaceEqual $l]
+} -result [list {0 1 2 3 99 4 5 6 7} 1]
+
+test listrep-1.4 {
+    Deletes from front of small unshared list with no free space should
+    just shift up leaving room at back - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceNone] $zero $zero]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {1 2 3 4 5 6 7} 0 1]
+
+test listrep-1.4.1 {
+    Deletes from front of small unshared list with no free space should
+    just shift up leaving room at back - lassign version
+} -constraints testlistrep -body {
+    set l [lassign [freeSpaceNone] e]
+    validate $l
+    list $e $l [leadSpace $l] [tailSpace $l]
+} -result [list 0 {1 2 3 4 5 6 7} 0 1]
+
+test listrep-1.4.2 {
+    Deletes from front of small unshared list with no free space should
+    just shift up leaving room at back - lpop version
+} -constraints testlistrep -body {
+    set l [freeSpaceNone]
+    set e [lpop l $zero]
+    validate $l
+    list $e $l [leadSpace $l] [tailSpace $l]
+} -result [list 0 {1 2 3 4 5 6 7} 0 1]
+
+test listrep-1.4.3 {
+    Deletes from front of small unshared list with no free space should
+    just shift up leaving room at back - lrange version
+} -constraints testlistrep -body {
+    set l [lrange [freeSpaceNone] $one $end]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {1 2 3 4 5 6 7} 0 1]
+
+test listrep-1.4.4 {
+    Deletes from front of small unshared list with no free space should
+    just shift up leaving room at back - lremove version
+} -constraints testlistrep -body {
+    set l [lremove [freeSpaceNone] $zero]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {1 2 3 4 5 6 7} 0 1]
+
+test listrep-1.5 {
+    Deletes from front of large unshared list with no free space should
+    create a span - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceNone 1000] $zero $one]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l 2 998]
+} -result [list [irange 2 999] 2 0 1]
+
+test listrep-1.5.1 {
+    Deletes from front of large unshared list with no free space should
+    create a span - lassign version
+} -constraints testlistrep -body {
+    set l [lassign [freeSpaceNone 1000] e]
+    validate $l
+    list $e $l [leadSpace $l] [tailSpace $l] [hasSpan $l 1 999]
+} -result [list 0 [irange 1 999] 1 0 1]
+
+test listrep-1.5.2 {
+    Deletes from front of large unshared list with no free space should
+    create a span - lrange version
+} -constraints testlistrep -body {
+    set l [lrange [freeSpaceNone 1000] $two end]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l 2 998]
+} -result [list [irange 2 999] 2 0 1]
+
+test listrep-1.5.3 {
+    Deletes from front of large unshared list with no free space should
+    create a span - lremove version
+} -constraints testlistrep -body {
+    set l [lremove [freeSpaceNone 1000] $zero]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l 1 999]
+} -result [list [irange 1 999] 1 0 1]
+
+test listrep-1.5.4 {
+    Deletes from front of large unshared list with no free space should
+    create a span - lpop version
+} -constraints testlistrep -body {
+    set l [freeSpaceNone 1000]
+    set e [lpop l 0]
+    validate $l
+    list $e $l [leadSpace $l] [tailSpace $l] [hasSpan $l 1 999]
+} -result [list 0 [irange 1 999] 1 0 1]
+
+test listrep-1.6 {
+    Deletes closer to front of large list should move (smaller) front segment
+    -- lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceNone 1000] $four $four]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l 1 999]
+} -result [list [concat [irange 0 3] [irange 5 999]] 1 0 1]
+
+test listrep-1.6.1 {
+    Deletes closer to front of large list should move (smaller) front segment
+    -- lpop version
+} -constraints testlistrep -body {
+    set l [freeSpaceNone 1000]
+    set e [lpop l $four]
+    validate $l
+    list $e $l [leadSpace $l] [tailSpace $l] [hasSpan $l 1 999]
+} -result [list 4 [concat [irange 0 3] [irange 5 999]] 1 0 1]
+
+test listrep-1.7 {
+    Deletes closer to back of large list should move (smaller) back segment
+    and will not need a span - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceNone 1000] end-$four end-$four]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l]
+} -result [list [concat [irange 0 994] [irange 996 999]] 0 1 0]
+
+test listrep-1.7.1 {
+    Deletes closer to back of large list should move (smaller) back segment
+    and will not need a span - lpop version
+} -constraints testlistrep -body {
+    set l [freeSpaceNone 1000]
+    set e [lpop l $end-4]
+    validate $l
+    list $e $l [leadSpace $l] [tailSpace $l] [hasSpan $l]
+} -result [list 995 [concat [irange 0 994] [irange 996 999]] 0 1 0]
+
+test listrep-1.8 {
+    Deletes at back of small unshared list should not need a span - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceNone] end-$one end]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l]
+} -result [list {0 1 2 3 4 5} 0 2 0]
+
+test listrep-1.8.1 {
+    Deletes at back of small unshared list should not need a span - lrange version
+} -constraints testlistrep -body {
+    set l [lrange [freeSpaceNone] $zero end-$two]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l]
+} -result [list {0 1 2 3 4 5} 0 2 0]
+
+test listrep-1.8.2 {
+    Deletes at back of small unshared list should not need a span - lremove version
+} -constraints testlistrep -body {
+    set l [lremove [freeSpaceNone] $end-1 $end]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l]
+} -result [list {0 1 2 3 4 5} 0 2 0]
+
+test listrep-1.8.3 {
+    Deletes at back of small unshared list should not need a span - lpop version
+} -constraints testlistrep -body {
+    set l [freeSpaceNone]
+    set e [lpop l $end]
+    validate $l
+    list $e $l [leadSpace $l] [tailSpace $l] [hasSpan $l]
+} -result [list 7 {0 1 2 3 4 5 6} 0 1 0]
+
+test listrep-1.9 {
+    Deletes at back of large unshared list should not need a span - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceNone 1000] end-$four end]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l]
+} -result [list [irange 0 994] 0 5 0]
+
+test listrep-1.9.1 {
+    Deletes at back of large unshared list should not need a span - lrange version
+} -constraints testlistrep -body {
+    set l [lrange [freeSpaceNone 1000] 0 $end-5]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l]
+} -result [list [irange 0 994] 0 5 0]
+
+test listrep-1.9.2 {
+    Deletes at back of large unshared list should not need a span - lremove version
+} -constraints testlistrep -body {
+    set l [lremove [freeSpaceNone 1000] end-$four $end-3 end-$two $end-1 $end]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l]
+} -result [list [irange 0 994] 0 5 0]
+
+test listrep-1.9.3 {
+    Deletes at back of large unshared list should not need a span - lpop version
+} -constraints testlistrep -body {
+    set l [freeSpaceNone 1000]
+    set e [lpop l $end]
+    validate $l
+    list $e $l [leadSpace $l] [tailSpace $l] [hasSpan $l]
+} -result [list 999 [irange 0 998] 0 1 0]
+
+test listrep-1.10 {
+    no-op on unshared list should force a canonical list string - lreplace version
+} -body {
+    lreplace {    1 2   3 4   } $zero -1
+} -result {1 2 3 4}
+
+test listrep-1.10.1 {
+    no-op on unshared list should force a canonical list string - lrange version
+} -body {
+    lrange {    1 2   3 4   } $zero $end
+} -result {1 2 3 4}
+
+test listrep-1.11 {
+    Append elements to large unshared list is optimized as lappend
+    so no free space in front - lreplace version
+} -body {
+    # Note $end, not end else byte code compiler short-cuts
+    set l [lreplace [freeSpaceNone 1000] $end+1 $end+1 1000]
+    validate $l
+    list $l [leadSpace $l] [expr {[tailSpace $l] > 0}] [hasSpan $l]
+} -result [list [irange 0 1000] 0 1 0]
+
+test listrep-1.11.1 {
+    Append elements to large unshared list is optimized as lappend
+    so no free space in front - linsert version
+} -body {
+    # Note $end, not end else byte code compiler short-cuts
+    set l [linsert [freeSpaceNone 1000] $end+1 1000]
+    validate $l
+    list $l [leadSpace $l] [expr {[tailSpace $l] > 0}] [hasSpan $l]
+} -result [list [irange 0 1000] 0 1 0]
+
+test listrep-1.11.2 {
+    Append elements to large unshared list leaves no free space in front
+    - lappend version
+} -body {
+    # Note $end, not end else byte code compiler short-cuts
+    set l [freeSpaceNone 1000]
+    lappend l 1000 1001
+    validate $l
+    list $l [leadSpace $l] [expr {[tailSpace $l] > 0}] [hasSpan $l]
+} -result [list [irange 0 1001] 0 1 0]
+
+
+test listrep-1.12 {
+    Replacement of elements at front with same number elements in unshared list
+    is in-place - lreplace version
+} -body {
+    set l [lreplace [freeSpaceNone] $zero $one 10 11]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {10 11 2 3 4 5 6 7} 0 0]
+
+test listrep-1.12.1 {
+    Replacement of elements at front with same number elements in unshared list
+    is in-place - lset version
+} -body {
+    set l [freeSpaceNone]
+    lset l 0 -1
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {-1 1 2 3 4 5 6 7} 0 0]
+
+test listrep-1.13 {
+    Replacement of elements at front with fewer elements in unshared list
+    results in a spanned list with space only in front
+} -body {
+    set l [lreplace [freeSpaceNone] $zero $four 10]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {10 5 6 7} 4 0]
+
+test listrep-1.14 {
+    Replacement of elements at front with more elements in unshared list
+    results in a reallocated spanned list with space at front and back
+} -body {
+    set l [lreplace [freeSpaceNone] $zero $one 10 11 12]
+    validate $l
+    list $l [spaceEqual $l]
+} -result [list {10 11 12 2 3 4 5 6 7} 1]
+
+test listrep-1.15 {
+    Replacement of elements in middle with same number elements in unshared list
+    is in-place - lreplace version
+} -body {
+    set l [lreplace [freeSpaceNone] $one $two 10 11]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 10 11 3 4 5 6 7} 0 0]
+
+test listrep-1.15.1 {
+    Replacement of elements in middle with same number elements in unshared list
+    is in-place - lset version
+} -body {
+    set l [freeSpaceNone]
+    lset l $two -1
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 -1 3 4 5 6 7} 0 0]
+
+test listrep-1.16 {
+    Replacement of elements in front half with fewer elements in unshared list
+    results in a spanned list with space only in front since smaller segment moved
+} -body {
+    set l [lreplace [freeSpaceNone] $one $four 10]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 10 5 6 7} 3 0]
+
+test listrep-1.17 {
+    Replacement of elements in back half with fewer elements in unshared list
+    results in a spanned list with space only at back
+} -body {
+    set l [lreplace [freeSpaceNone] end-$four end-$one 10]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 2 10 7} 0 3]
+
+test listrep-1.18 {
+    Replacement of elements in middle more elements in unshared list
+    results in a reallocated spanned list with space at front and back
+} -body {
+    set l [lreplace [freeSpaceNone] $one $two 10 11 12]
+    validate $l
+    list $l [spaceEqual $l]
+} -result [list {0 10 11 12 3 4 5 6 7} 1]
+
+test listrep-1.19 {
+    Replacement of elements at back with same number elements in unshared list
+    is in-place - lreplace version
+} -body {
+    set l [lreplace [freeSpaceNone] $end-1 $end 10 11]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 2 3 4 5 10 11} 0 0]
+
+test listrep-1.19.1 {
+    Replacement of elements at back with same number elements in unshared list
+    is in-place - lset version
+} -body {
+    set l [freeSpaceNone]
+    lset l $end 10
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 2 3 4 5 6 10} 0 0]
+
+test listrep-1.20 {
+    Replacement of elements at back with fewer elements in unshared list
+    is in-place with space only at the back
+} -body {
+    set l [lreplace [freeSpaceNone] $end-2 $end 10]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 2 3 4 10} 0 2]
+
+test listrep-1.21 {
+    Replacement of elements at back with more elements in unshared list
+    allocates new representation with equal space at front and back
+} -body {
+    set l [lreplace [freeSpaceNone] $end-1 $end 10 11 12]
+    validate $l
+    list $l [spaceEqual $l]
+} -result [list {0 1 2 3 4 5 10 11 12} 1]
+
+#
+# listrep-2.* tests all operate on shared list reps with no free space. Note the
+# *list internal rep* must be shared, not only the Tcl_Obj so just assigning to
+# another variable does not suffice. The lrange construct on an variable's value
+# will do the needful.
+
+test listrep-2.1 {
+    Inserts in front of shared list with no free space should reallocate with
+    more leading space in front - linsert version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [linsert $b $zero 99]
+    validate $l
+    list [repStoreRefCount $b] $l [leadSpaceMore $l] [repStoreRefCount $l]
+} -result [list 2 {99 0 1 2 3 4 5 6 7} 1 1]
+
+test listrep-2.1.1 {
+    Inserts in front of shared list with no free space should reallocate with
+    more leading space in front - lreplace version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lreplace $b $zero -1 99]
+    validate $l
+    list [repStoreRefCount $b] $l [leadSpaceMore $l] [repStoreRefCount $l]
+} -result [list 2 {99 0 1 2 3 4 5 6 7} 1 1]
+
+test listrep-2.2 {
+    Inserts at back of shared list with no free space should reallocate with
+    more leading space in back - linsert version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [linsert $b $end 99]
+    validate $l
+    list [repStoreRefCount $b] $l [tailSpaceMore $l] [repStoreRefCount $l]
+} -result [list 2 {0 1 2 3 4 5 6 7 99} 1 1]
+
+test listrep-2.2.1 {
+    Inserts at back of shared list with no free space should reallocate with
+    more leading space in back - lreplace version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lreplace $b $end+1 end+$one 99]
+    validate $l
+    list [repStoreRefCount $b] $l [tailSpaceMore $l] [repStoreRefCount $l]
+} -result [list 2 {0 1 2 3 4 5 6 7 99} 1 1]
+
+test listrep-2.2.2 {
+    Inserts at back of shared list with no free space should reallocate with
+    more leading space in back - lappend version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lappend b 99]
+    validate $l
+    list [repStoreRefCount $b] $l [tailSpaceMore $l] [repStoreRefCount $l]
+} -result [list 1 {0 1 2 3 4 5 6 7 99} 1 1]
+
+test listrep-2.2.3 {
+    Inserts at back of shared list with no free space should reallocate with
+    more leading space in back - lset version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lset b $end+1 99]
+    validate $l
+    list [repStoreRefCount $b] $l [tailSpaceMore $l] [repStoreRefCount $l]
+} -result [list 1 {0 1 2 3 4 5 6 7 99} 1 1]
+
+test listrep-2.3 {
+    Inserts in middle of shared list with no free space should reallocate with
+    equal spacing - linsert version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [linsert $b $four 99]
+    validate $l
+    list [repStoreRefCount $b] $l [spaceEqual $l] [repStoreRefCount $l]
+} -result [list 2 {0 1 2 3 99 4 5 6 7} 1 1]
+
+test listrep-2.3.1 {
+    Inserts in middle of shared list with no free space should reallocate with
+    equal spacing - lreplace version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lreplace $b $four $four-1 99]
+    validate $l
+    list [repStoreRefCount $b] $l [spaceEqual $l] [repStoreRefCount $l]
+} -result [list 2 {0 1 2 3 99 4 5 6 7} 1 1]
+
+test listrep-2.4 {
+    Deletes from front of small shared list with no free space should
+    allocate new list of exact size - lreplace version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lreplace $b $zero $zero]
+    validate $l
+    list [repStoreRefCount $b] $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 2 {1 2 3 4 5 6 7} 0 0 1]
+
+test listrep-2.4.1 {
+    Deletes from front of small shared list with no free space should
+    allocate new list of exact size - lremove version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lremove $b $zero $one]
+    validate $l
+    list [repStoreRefCount $b] $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 2 {2 3 4 5 6 7} 0 0 1]
+
+test listrep-2.4.2 {
+    Deletes from front of small shared list with no free space should
+    allocate new list of exact size - lrange version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lrange $b $one $end]
+    validate $l
+    list [repStoreRefCount $b] $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 2 {1 2 3 4 5 6 7} 0 0 1]
+
+test listrep-2.4.3 {
+    Deletes from front of small shared list with no free space should
+    allocate new list of exact size - lassign version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lassign $b e]
+    validate $l
+    list $e [repStoreRefCount $b] $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 0 2 {1 2 3 4 5 6 7} 0 0 1]
+
+test listrep-2.4.4 {
+    Deletes from front of small shared list with no free space should
+    allocate new list of exact size - lpop version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set l [lrange $a $zero end]; # Ensure shared listrep
+    set e [lpop l $zero]
+    validate $l
+    list $e $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 0 {1 2 3 4 5 6 7} 0 0 1]
+
+test listrep-2.5 {
+    Deletes from front of large shared list with no free space should
+    create span - lreplace version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone 1000]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lreplace $b $zero $zero]
+    validate $l
+    # The listrep store should be shared among a, b, l (3 refs)
+    list [sameStore $b $l] [repStoreRefCount $b] $l [hasSpan $l] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 1 3 [irange 1 999] 1 0 0 3]
+
+test listrep-2.5.1 {
+    Deletes from front of large shared list with no free space should
+    create span - lremove version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone 1000]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lremove $b $zero $one]
+    validate $l
+    # The listrep store should be shared among a, b, l (3 refs)
+    list [sameStore $b $l] [repStoreRefCount $b] $l [hasSpan $l] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 1 3 [irange 2 999] 1 0 0 3]
+
+test listrep-2.5.2 {
+    Deletes from front of large shared list with no free space should
+    create span - lrange version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone 1000]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lrange $b $two $end]
+    validate $l
+    # The listrep store should be shared among a, b, l (3 refs)
+    list [sameStore $b $l] [repStoreRefCount $b] $l [hasSpan $l] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 1 3 [irange 2 999] 1 0 0 3]
+
+test listrep-2.5.3 {
+    Deletes from front of large shared list with no free space should
+    create span - lassign version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone 1000]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lassign $b e]
+    validate $l
+    # The listrep store should be shared among a, b, l (3 refs)
+    list $e [sameStore $b $l] [repStoreRefCount $b] $l [hasSpan $l] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 0 1 3 [irange 1 999] 1 0 0 3]
+
+test listrep-2.5.4 {
+    Deletes from front of large shared list with no free space should
+    create span - lpop version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone 1000]
+    set l [lrange $a $zero end]; # Ensure shared listrep
+    set e [lpop l $zero]
+    validate $l
+    # The listrep store should be shared among a, b, l (3 refs)
+    list $e $l [hasSpan $l] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 0 [irange 1 999] 1 0 0 2]
+
+test listrep-2.6 {
+    Deletes from back of small shared list with no free space should
+    allocate new list of exact size - lreplace version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lreplace $b $end $end]
+    validate $l
+    list [repStoreRefCount $b] $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 2 {0 1 2 3 4 5 6} 0 0 1]
+
+test listrep-2.6.1 {
+    Deletes from back of small shared list with no free space should
+    allocate new list of exact size - lremove version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lremove $b $end $end-1]
+    validate $l
+    list [repStoreRefCount $b] $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 2 {0 1 2 3 4 5} 0 0 1]
+
+test listrep-2.6.2 {
+    Deletes from back of small shared list with no free space should
+    allocate new list of exact size - lrange version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lrange $b $zero $end-1]
+    validate $l
+    list [repStoreRefCount $b] $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 2 {0 1 2 3 4 5 6} 0 0 1]
+
+test listrep-2.6.3 {
+    Deletes from back of small shared list with no free space should
+    allocate new list of exact size - lpop version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set l [lrange $a $zero end]; # Ensure shared listrep
+    set e [lpop l]
+    validate $l
+    list $e $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 7 {0 1 2 3 4 5 6} 0 0 1]
+
+test listrep-2.7 {
+    Deletes from back of large shared list with no free space should
+    use a span - lreplace version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone 1000]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lreplace $b $end $end]
+    validate $l
+    # Note lead and tail space is 0 because original list store in a,b is used
+    list [repStoreRefCount $b] $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 3 [irange 0 998] 0 0 3]
+
+test listrep-2.7.1 {
+    Deletes from back of large shared list with no free space should
+    use a span - lremove version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone 1000]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lremove $b $end-1 $end]
+    validate $l
+    # Note lead and tail space is 0 because original list store in a,b is used
+    list [repStoreRefCount $b] $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 3 [irange 0 997] 0 0 3]
+
+test listrep-2.7.2 {
+    Deletes from back of large shared list with no free space should
+    use a span - lrange version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone 1000]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lrange $b $zero $end-1]
+    validate $l
+    # Note lead and tail space is 0 because original list store in a,b is used
+    list [repStoreRefCount $b] $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 3 [irange 0 998] 0 0 3]
+
+test listrep-2.7.3 {
+    Deletes from back of large shared list with no free space should
+    use a span - lpop version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone 1000]
+    set l [lrange $a $zero end]; # Ensure shared listrep
+    set e [lpop l]
+    validate $l
+    # Note lead and tail space is 0 because original list store in a,b is used
+    list $e $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 999 [irange 0 998] 0 0 2]
+
+test listrep-2.8 {
+    no-op on shared list should force a canonical list representation
+    with original unchanged - lreplace version
+} -body {
+    set l {     1 2   3 4   }
+    list [lreplace $l $zero -1] $l
+} -result [list {1 2 3 4} {     1 2   3 4   }]
+
+test listrep-2.8.1 {
+    no-op on shared list should force a canonical list representation
+    with original unchanged - lrange version
+} -body {
+    set l {     1 2   3 4   }
+    list [lrange $l $zero end] $l
+} -result [list {1 2 3 4} {     1 2   3 4   }]
+
+test listrep-2.9 {
+    Appends to back of large shared list with no free space allocates new
+    list with space only at the back - lreplace version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone 1000]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lreplace $b $end+1 $end+1 1000]
+    validate $l
+    list [repStoreRefCount $b] $l [leadSpace $l] [expr {[tailSpace $l]>0}] [repStoreRefCount $l]
+} -result [list 2 [irange 0 1000] 0 1 1]
+
+test listrep-2.9.1 {
+    Appends to back of large shared list with no free space allocates new
+    list with space only at the back - linsert version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone 1000]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [linsert $b $end+1 1000 1001]
+    validate $l
+    list [repStoreRefCount $b] $l [leadSpace $l] [expr {[tailSpace $l]>0}] [repStoreRefCount $l]
+} -result [list 2 [irange 0 1001] 0 1 1]
+
+test listrep-2.9.2 {
+    Appends to back of large shared list with no free space allocates new
+    list with space only at the back - lappend version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone 1000]
+    set l [lrange $a $zero end]; # Ensure shared listrep
+    lappend l 1000
+    validate $l
+    list $l [leadSpace $l] [expr {[tailSpace $l]>0}] [repStoreRefCount $l]
+} -result [list [irange 0 1000] 0 1 1]
+
+test listrep-2.9.3 {
+    Appends to back of large shared list with no free space allocates new
+    list with space only at the back - lset version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone 1000]
+    set l [lrange $a $zero end]; # Ensure shared listrep
+    lset l $end+1 1000
+    validate $l
+    list $l [leadSpace $l] [expr {[tailSpace $l]>0}] [repStoreRefCount $l]
+} -result [list [irange 0 1000] 0 1 1]
+
+test listrep-2.10 {
+    Replacement of elements at front with same number in shared list results
+    in a new list store with more space in front than back - lreplace version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lreplace $b $zero $one 10 11]
+    validate $l
+    list [repStoreRefCount $b] $l [leadSpaceMore $l] [repStoreRefCount $l]
+} -result [list 2 {10 11 2 3 4 5 6 7} 1 1]
+
+test listrep-2.10.1 {
+    Replacement of elements at front with same number in shared list results
+    in a new list store with no extra space - lset version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set l [lrange $a $zero end]; # Ensure shared listrep
+    lset l $zero 10
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {10 1 2 3 4 5 6 7} 0 0 1]
+
+test listrep-2.11 {
+    Replacement of elements at front with fewer elements in shared list
+    results in a new list store with more space in front than back
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lreplace $b $zero $four 10]
+    validate $l
+    list [repStoreRefCount $b] $l [leadSpaceMore $l] [repStoreRefCount $l]
+} -result [list 2 {10 5 6 7} 1 1]
+
+test listrep-2.12 {
+    Replacement of elements at front with more elements in shared list
+    results in a new spanned list with more space in front
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lreplace $b $zero $one 10 11 12]
+    validate $l
+    list [repStoreRefCount $b] $l [leadSpaceMore $l] [repStoreRefCount $l]
+} -result [list 2 {10 11 12 2 3 4 5 6 7} 1 1]
+
+test listrep-2.13 {
+    Replacement of elements in middle with same number in shared list results
+    in a new list store with equal space in front and back - lreplace version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lreplace $b $one $two 10 11]
+    validate $l
+    list [repStoreRefCount $b] $l [spaceEqual $l] [repStoreRefCount $l]
+} -result [list 2 {0 10 11 3 4 5 6 7} 1 1]
+
+test listrep-2.13.1 {
+    Replacement of elements in middle with same number in shared list results
+    in a new list store with exact allocation - lset version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set l [lrange $a $zero end]; # Ensure shared listrep
+    lset l $one 10
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {0 10 2 3 4 5 6 7} 0 0 1]
+
+test listrep-2.14 {
+    Replacement of elements in middle with fewer elements in shared list
+    results in a new list store with equal space
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lreplace $b $one 5 10]
+    validate $l
+    list [repStoreRefCount $b] $l [spaceEqual $l] [repStoreRefCount $l]
+} -result [list 2 {0 10 6 7} 1 1]
+
+test listrep-2.15 {
+    Replacement of elements in middle with more elements in shared list
+    results in a new spanned list with space in front and back
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lreplace $b $one $two 10 11 12]
+    validate $l
+    list [repStoreRefCount $b] $l [spaceEqual $l] [repStoreRefCount $l]
+} -result [list 2 {0 10 11 12 3 4 5 6 7} 1 1]
+
+test listrep-2.16 {
+    Replacement of elements at back with same number in shared list results
+    in a new list store with more space in back than front - lreplace version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lreplace $b end-$one $end 10 11]
+    validate $l
+    list [repStoreRefCount $b] $l [tailSpaceMore $l] [repStoreRefCount $l]
+} -result [list 2 {0 1 2 3 4 5 10 11} 1 1]
+
+test listrep-2.16.1 {
+    Replacement of elements at back with same number in shared list results
+    in a new list store with no extra - lreplace version
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set l [lrange $a $zero end]; # Ensure shared listrep
+    lset l $end 10
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {0 1 2 3 4 5 6 10} 0 0 1]
+
+test listrep-2.17 {
+    Replacement of elements at back with fewer elements in shared list
+    results in a new list store with more space in back than front
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lreplace $b end-$four $end 10]
+    validate $l
+    list [repStoreRefCount $b] $l [tailSpaceMore $l] [repStoreRefCount $l]
+} -result [list 2 {0 1 2 10} 1 1]
+
+test listrep-2.18 {
+    Replacement of elements at back with more elements in shared list
+    results in a new list store with more space in back than front
+} -constraints testlistrep -body {
+    set a [freeSpaceNone]
+    set b [lrange $a $zero end]; # Ensure shared listrep
+    set l [lreplace $b end-$four $end 10]
+    validate $l
+    list [repStoreRefCount $b] $l [tailSpaceMore $l] [repStoreRefCount $l]
+} -result [list 2 {0 1 2 10} 1 1]
+
+#
+# listrep-3.* - tests on unshared spanned listreps
+
+test listrep-3.1 {
+    Inserts in front of unshared spanned list with room in front should just
+    shrink the lead space - linsert version
+} -constraints testlistrep -body {
+    set l [linsert [freeSpaceBoth] $zero -2 -1]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange -2 7] 1 3 1]
+
+test listrep-3.1.1 {
+    Inserts in front of unshared spanned list with room in front should just
+    shrink the lead space - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth] $zero -1 -2 -1]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange -2 7] 1 3 1]
+
+test listrep-3.2 {
+    Inserts in front of unshared spanned list with insufficient room in front
+    but enough total freespace should redistribute free space - linsert version
+} -constraints testlistrep -body {
+    set l [linsert [freeSpaceBoth 8 1 10] $zero -2 -1]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange -2 7] 5 4 1]
+
+test listrep-3.2.1 {
+    Inserts in front of unshared spanned list with insufficient room in front
+    but enough total freespace should redistribute free space - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth 8 1 10] $zero -1 -2 -1]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange -2 7] 5 4 1]
+
+test listrep-3.3 {
+    Inserts in front of unshared spanned list with insufficient total freespace
+    should reallocate with equal free space - linsert version
+} -constraints testlistrep -body {
+    set l [linsert [freeSpaceBoth 8 1 1] $zero -3 -2 -1]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange -3 7] 6 5 1]
+
+test listrep-3.3.1 {
+    Inserts in front of unshared spanned list with insufficient total freespace
+    should reallocate with equal free space - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth 8 1 1] $zero -1 -3 -2 -1]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange -3 7] 6 5 1]
+
+test listrep-3.4 {
+    Inserts at back of unshared spanned list with room at back should not
+    reallocate - linsert version
+} -constraints testlistrep -body {
+    set l [linsert [freeSpaceBoth] $end 8]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange 0 8] 3 2 1]
+
+test listrep-3.4.1 {
+    Inserts at back of unshared spanned list with room at back should not
+    reallocate - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth] $end+1 $end+1 8 9]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange 0 9] 3 1 1]
+
+test listrep-3.4.2 {
+    Inserts at back of unshared spanned list with room at back should not
+    reallocate - lappend version
+} -constraints testlistrep -body {
+    set l [freeSpaceBoth]
+    lappend l 8 9 10
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange 0 10] 3 0 1]
+
+test listrep-3.4.3 {
+    Inserts at back of unshared spanned list with room at back should not
+    reallocate - lset version
+} -constraints testlistrep -body {
+    set l [freeSpaceBoth]
+    lset l $end+1 8
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange 0 8] 3 2 1]
+
+test listrep-3.5 {
+    Inserts at back of unshared spanned list with insufficient room in back
+    but enough total freespace should redistribute free space - linsert version
+} -constraints testlistrep -body {
+    set l [linsert [freeSpaceBoth 8 10 1] $end 8 9]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange 0 9] 5 4 1]
+
+test listrep-3.5.1 {
+    Inserts at back of unshared spanned list with insufficient room in back
+    but enough total freespace should redistribute free space - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth 8 10 1] $end+1 $end+1 8 9]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange 0 9] 5 4 1]
+
+test listrep-3.5.2 {
+    Inserts at back of unshared spanned list with insufficient room in back
+    but enough total freespace should redistribute free space - lappend version
+} -constraints testlistrep -body {
+    set l [freeSpaceBoth 8 10 1]
+    lappend l 8 9
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange 0 9] 5 4 1]
+
+test listrep-3.5.3 {
+    Inserts at back of unshared spanned list with insufficient room in back
+    but enough total freespace should redistribute free space - lset version
+} -constraints testlistrep -body {
+    set l [freeSpaceBoth 8 10 0]
+    lset l $end+1 8
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange 0 8] 5 4 1]
+
+test listrep-3.6 {
+    Inserts in back of unshared spanned list with insufficient total freespace
+    should reallocate with all *additional* space at back. Note this differs
+    from the insert in front case because here we realloc(). - linsert version
+} -constraints testlistrep -body {
+    set l [linsert [freeSpaceBoth 8 1 1] $end 8 9 10]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange 0 10] 1 10 1]
+
+test listrep-3.6.1 {
+    Inserts in back of unshared spanned list with insufficient total freespace
+    should reallocate with all *additional* space at back. Note this differs
+    from the insert in front case because here we realloc() - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth 8 1 1] $end+1 $end+1 8 9 10]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange 0 10] 1 10 1]
+
+test listrep-3.6.2 {
+    Inserts in back of unshared spanned list with insufficient total freespace
+    should reallocate with all *additional* space at back. Note this differs
+    from the insert in front case because here we realloc() - lappend version
+} -constraints testlistrep -body {
+    set l [freeSpaceBoth 8 1 1]
+    lappend l 8 9 10
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange 0 10] 1 10 1]
+
+test listrep-3.6.3 {
+    Inserts in back of unshared spanned list with insufficient total freespace
+    should reallocate with all *additional* space at back. Note this differs
+    from the insert in front case because here we realloc() - lset version
+} -constraints testlistrep -body {
+    set l [freeSpaceNone]
+    lset l $end+1 8
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange 0 8] 0 9 1]
+
+test listrep-3.7 {
+    Inserts in front half of unshared spanned list with room in front should not
+    reallocate and should move front segment
+} -constraints testlistrep -body {
+    set l [linsert [freeSpaceBoth] $one -2 -1]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {0 -2 -1 1 2 3 4 5 6 7} 1 3 1]
+
+test listrep-3.8 {
+    Inserts in front half of unshared spanned list with insufficient leading
+    space but with enough tail space - linsert version
+} -constraints testlistrep -body {
+    set l [linsert [freeSpaceBoth 8 1 5] $one -2 -1]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {0 -2 -1 1 2 3 4 5 6 7} 1 3 1]
+
+test listrep-3.8.1 {
+    Inserts in front half of unshared spanned list with insufficient leading
+    space but with enough tail space - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth 8 1 5] $one -1 -2 -1]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {0 -2 -1 1 2 3 4 5 6 7} 1 3 1]
+
+test listrep-3.9 {
+    Inserts in front half of unshared spanned list with sufficient total
+    free space - linsert version
+} -constraints testlistrep -body {
+    set l [linsert [freeSpaceBoth 8 2 2] $one -3 -2 -1]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {0 -3 -2 -1 1 2 3 4 5 6 7} 0 1 1]
+
+test listrep-3.9.1 {
+    Inserts in front half of unshared spanned list with sufficient total
+    free space - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth 8 2 2] $one -1 -3 -2 -1]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {0 -3 -2 -1 1 2 3 4 5 6 7} 0 1 1]
+
+test listrep-3.10 {
+    Inserts in front half of unshared spanned list with insufficient total space.
+    Note use of realloc() means new space will be at the back - linsert version
+} -constraints testlistrep -body {
+    set l [linsert [freeSpaceBoth 8 1 1] $one -3 -2 -1]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {0 -3 -2 -1 1 2 3 4 5 6 7} 1 10 1]
+
+test listrep-3.10.1 {
+    Inserts in front half of unshared spanned list with insufficient total space.
+    Note use of realloc() means new space will be at the back - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth 8 1 1] $one -1 -3 -2 -1]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {0 -3 -2 -1 1 2 3 4 5 6 7} 1 10 1]
+
+test listrep-3.11 {
+    Inserts in back half of unshared spanned list with room in back should not
+    reallocate and should move back segment - linsert version
+} -constraints testlistrep -body {
+    set l [linsert [freeSpaceBoth] $end-$one 8 9]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {0 1 2 3 4 5 6 8 9 7} 3 1 1]
+
+test listrep-3.11.1 {
+    Inserts in back half of unshared spanned list with room in back should not
+    reallocate and should move back segment - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth] $end -1 8 9]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {0 1 2 3 4 5 6 8 9 7} 3 1 1]
+
+test listrep-3.12 {
+    Inserts in back half of unshared spanned list with insufficient tail
+    space but with enough leading space - linsert version
+} -constraints testlistrep -body {
+    set l [linsert [freeSpaceBoth 8 5 1] $end-$one 8 9]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {0 1 2 3 4 5 6 8 9 7} 3 1 1]
+
+test listrep-3.12.1 {
+    Inserts in back half of unshared spanned list with insufficient tail
+    space but with enough leading space - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth 8 5 1] $end -1 8 9]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {0 1 2 3 4 5 6 8 9 7} 3 1 1]
+
+test listrep-3.13 {
+    Inserts in back half of unshared spanned list with sufficient total
+    free space - linsert version
+} -constraints testlistrep -body {
+    set l [linsert [freeSpaceBoth 8 2 2] $end-$one 8 9 10]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {0 1 2 3 4 5 6 8 9 10 7} 0 1 1]
+
+test listrep-3.13.1 {
+    Inserts in back half of unshared spanned list with sufficient total
+    free space - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth 8 2 2] $end -1 8 9 10]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {0 1 2 3 4 5 6 8 9 10 7} 0 1 1]
+
+test listrep-3.14 {
+    Inserts in back half of unshared spanned list with insufficient
+    total space. Note use of realloc() means new space will be at the
+    back - linsert version
+} -constraints testlistrep -body {
+    set l [linsert [freeSpaceBoth 8 1 1] $end-$one 8 9 10]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {0 1 2 3 4 5 6 8 9 10 7} 1 10 1]
+
+test listrep-3.14.1 {
+    Inserts in back half of unshared spanned list with insufficient
+    total space. Note use of realloc() means new space will be at the
+    back - lrepalce version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth 8 1 1] $end -1 8 9 10]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {0 1 2 3 4 5 6 8 9 10 7} 1 10 1]
+
+test listrep-3.15 {
+    Deletes from front of small unshared span list results in elements
+    moved up front and span removal - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth] $zero $zero]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l]
+} -result [list {1 2 3 4 5 6 7} 0 7 0]
+
+test listrep-3.15.1 {
+    Deletes from front of small unshared span list results in elements
+    moved up front and span removal - lremove version
+} -constraints testlistrep -body {
+    set l [lremove [freeSpaceBoth] $zero $one]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l]
+} -result [list {2 3 4 5 6 7} 0 8 0]
+
+test listrep-3.15.2 {
+    Deletes from front of small unshared span list results in elements
+    moved up front and span removal - lrange version
+} -constraints testlistrep -body {
+    set l [lrange [freeSpaceBoth] $one $end]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l]
+} -result [list {1 2 3 4 5 6 7} 0 7 0]
+
+test listrep-3.15.3 {
+    Deletes from front of small unshared span list results in elements
+    moved up front and span removal - lassign version
+} -constraints testlistrep -body {
+    set l [lassign [freeSpaceBoth] e]
+    validate $l
+    list $e $l [leadSpace $l] [tailSpace $l] [hasSpan $l]
+} -result [list 0 {1 2 3 4 5 6 7} 0 7 0]
+
+test listrep-3.15.4 {
+    Deletes from front of small unshared span list results in elements
+    moved up front and span removal - lpop version
+} -constraints testlistrep -body {
+    set l [freeSpaceBoth]
+    set e [lpop l $zero]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l]
+} -result [list {1 2 3 4 5 6 7} 0 7 0]
+
+test listrep-3.16 {
+    Deletes from front of large unshared span list results in another
+    span - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth 1000 10 10] $zero $one]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l 12 998]
+} -result [list [irange 2 999] 12 10 1]
+
+test listrep-3.16.1 {
+    Deletes from front of large unshared span list results in another
+    span - lremove version
+} -constraints testlistrep -body {
+    set l [lremove [freeSpaceBoth 1000 10 10] $zero $one]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l 12 998]
+} -result [list [irange 2 999] 12 10 1]
+
+test listrep-3.16.2 {
+    Deletes from front of large unshared span list results in another
+    span - lrange version
+} -constraints testlistrep -body {
+    set l [lrange [freeSpaceBoth 1000 10 10] $two $end]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l 12 998]
+} -result [list [irange 2 999] 12 10 1]
+
+test listrep-3.16.3 {
+    Deletes from front of large unshared span list results in another
+    span - lassign version
+} -constraints testlistrep -body {
+    set l [lassign [freeSpaceBoth 1000 10 10] e]
+    validate $l
+    list $e $l [leadSpace $l] [tailSpace $l] [hasSpan $l 11 999]
+} -result [list 0 [irange 1 999] 11 10 1]
+
+test listrep-3.16.4 {
+    Deletes from front of large unshared span list results in another
+    span - lpop version
+} -constraints testlistrep -body {
+    set l [freeSpaceBoth 1000 10 10]
+    set e [lpop l $zero]
+    validate $l
+    list $e $l [leadSpace $l] [tailSpace $l] [hasSpan $l 11 999]
+} -result [list 0 [irange 1 999] 11 10 1]
+
+test listrep-3.17 {
+    Deletes from back of small unshared span list results in new store
+    without span - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth] $end $end]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l]
+} -result [list {0 1 2 3 4 5 6} 0 7 0]
+
+test listrep-3.17.1 {
+    Deletes from back of small unshared span list results in new store
+    without span - lremove version
+} -constraints testlistrep -body {
+    set l [lremove [freeSpaceBoth] $end]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l]
+} -result [list {0 1 2 3 4 5 6} 0 7 0]
+
+test listrep-3.17.2 {
+    Deletes from back of small unshared span list results in new store
+    without span - lrange version
+} -constraints testlistrep -body {
+    set l [lrange [freeSpaceBoth] $zero $end-1]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l]
+} -result [list {0 1 2 3 4 5 6} 0 7 0]
+
+test listrep-3.17.3 {
+    Deletes from back of small unshared span list results in new store
+    without span - lpop version
+} -constraints testlistrep -body {
+    set l [freeSpaceBoth]
+    set e [lpop l]
+    validate $l
+    list $e $l [leadSpace $l] [tailSpace $l] [hasSpan $l]
+} -result [list 7 {0 1 2 3 4 5 6} 0 7 0]
+
+test listrep-3.18 {
+    Deletes from back of large unshared span list results in another
+    span - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth 1000 10 10] $end-1 $end]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l 10 998]
+} -result [list [irange 0 997] 10 12 1]
+
+test listrep-3.18.1 {
+    Deletes from back of large unshared span list results in another
+    span - lremove version
+} -constraints testlistrep -body {
+    set l [lremove [freeSpaceBoth 1000 10 10] $end-1 $end]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l 10 998]
+} -result [list [irange 0 997] 10 12 1]
+
+test listrep-3.18.2 {
+    Deletes from back of large unshared span list results in another
+    span - lrange version
+} -constraints testlistrep -body {
+    set l [lrange [freeSpaceBoth 1000 10 10] $zero $end-2]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l 10 998]
+} -result [list [irange 0 997] 10 12 1]
+
+test listrep-3.18.3 {
+    Deletes from back of large unshared span list results in another
+    span - lpop version
+} -constraints testlistrep -body {
+    set l [freeSpaceBoth 1000 10 10]
+    set e [lpop l]
+    validate $l
+    list $e $l [leadSpace $l] [tailSpace $l] [hasSpan $l 10 999]
+} -result [list 999 [irange 0 998] 10 11 1]
+
+test listrep-3.19 {
+    Deletes from front half of small unshared span list results in
+    movement of smaller front segment - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth] $one $two]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l 5 6]
+} -result [list {0 3 4 5 6 7} 5 3 1]
+
+test listrep-3.19.1 {
+    Deletes from front half of small unshared span list results in
+    movement of smaller front segment - lremove version
+} -constraints testlistrep -body {
+    set l [lremove [freeSpaceBoth] $one $two]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l 5 6]
+} -result [list {0 3 4 5 6 7} 5 3 1]
+
+test listrep-3.20 {
+    Deletes from front half of large unshared span list results in
+    movement of smaller front segment - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth 1000 10 10] $one $two]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l 12 998]
+} -result [list [list 0 {*}[irange 3 999]] 12 10 1]
+
+test listrep-3.20.1 {
+    Deletes from front half of large unshared span list results in
+    movement of smaller front segment - lremove version
+} -constraints testlistrep -body {
+    set l [lremove [freeSpaceBoth 1000 10 10] $one $two]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l 12 998]
+} -result [list [list 0 {*}[irange 3 999]] 12 10 1]
+
+test listrep-3.21 {
+    Deletes from back half of small unshared span list results in
+    movement of smaller back segment - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth] $end-2 $end-1]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l 3 6]
+} -result [list {0 1 2 3 4 7} 3 5 1]
+
+test listrep-3.21.1 {
+    Deletes from back half of small unshared span list results in
+    movement of smaller back segment - lremove version
+} -constraints testlistrep -body {
+    set l [lremove [freeSpaceBoth] $end-2 $end-1]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l 3 6]
+} -result [list {0 1 2 3 4 7} 3 5 1]
+
+test listrep-3.22 {
+    Deletes from back half of large unshared span list results in
+    movement of smaller back segment - lreplace version
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth 1000 10 10] $end-2 $end-1]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l 10 998]
+} -result [list [list {*}[irange 0 996] 999] 10 12 1]
+
+test listrep-3.22.1 {
+    Deletes from back half of large unshared span list results in
+    movement of smaller back segment - lremove version
+} -constraints testlistrep -body {
+    set l [lremove [freeSpaceBoth 1000 10 10] $end-2 $end-1]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [hasSpan $l 10 998]
+} -result [list [list {*}[irange 0 996] 999] 10 12 1]
+
+test listrep-3.23 {
+    Replacement of elements at front with same number elements in unshared
+    spanned list is in-place - lreplace version
+} -body {
+    set l [lreplace [freeSpaceBoth] $zero $one 10 11]
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {10 11 2 3 4 5 6 7} 3 3]
+
+test listrep-3.23.1 {
+    Replacement of elements at front with same number elements in unshared
+    spanned list is in-place - lset version
+} -body {
+    set l [freeSpaceBoth]
+    lset l $zero 10
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {10 1 2 3 4 5 6 7} 3 3]
+
+test listrep-3.24 {
+    Replacement of elements at front with fewer elements in unshared
+    spanned list expands leading space - lreplace version
+} -body {
+    set l [lreplace [freeSpaceBoth] $zero $four 10]
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {10 5 6 7} 7 3]
+
+test listrep-3.25 {
+    Replacement of elements at front with more elements in unshared
+    spanned list with sufficient leading space shrinks leading space
+} -body {
+    set l [lreplace [freeSpaceBoth] $zero $one 10 11 12]
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {10 11 12 2 3 4 5 6 7} 2 3]
+
+test listrep-3.26 {
+    Replacement of elements at front with more elements in unshared
+    spanned list with insufficient leading space but sufficient total
+    free space
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth 8 1 10] $zero $one 10 11 12 13]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {10 11 12 13 2 3 4 5 6 7} 5 4 1]
+
+test listrep-3.27 {
+    Replacement of elements at front in unshared spanned list with insufficient
+    total freespace should reallocate with equal free space
+} -constraints testlistrep -body {
+    set l [lreplace [freeSpaceBoth 8 1 1] $zero $one 10 11 12 13 14]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list {10 11 12 13 14 2 3 4 5 6 7} 6 5 1]
+
+test listrep-3.28 {
+    Replacement of elements at back with same number of elements in unshared
+    spanned list is in-place - lreplace version
+} -body {
+    set l [lreplace [freeSpaceBoth] $end-1 $end 10 11]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 2 3 4 5 10 11} 3 3]
+
+test listrep-3.28.1 {
+    Replacement of elements at back with same number of elements in unshared
+    spanned list is in-place - lset version
+} -body {
+    set l [freeSpaceBoth]
+    lset l $end 10
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 2 3 4 5 6 10} 3 3]
+
+test listrep-3.29 {
+    Replacement of elements at back with fewer elements in unshared
+    spanned list expands tail space
+} -body {
+    set l [lreplace [freeSpaceBoth] $end-2 $end 10]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 2 3 4 10} 3 5]
+
+test listrep-3.30 {
+    Replacement of elements at back with more elements in unshared
+    spanned list with sufficient tail space shrinks tailspace
+} -body {
+    set l [lreplace [freeSpaceBoth] $end-1 $end 10 11 12]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 2 3 4 5 10 11 12} 3 2]
+
+test listrep-3.31 {
+    Replacement of elements at back with more elements in unshared spanned list
+    with insufficient tail space but enough total free space moves up the span
+} -body {
+    set l [lreplace [freeSpaceBoth 8 2 2] $end-1 $end 10 11 12 13 14]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 2 3 4 5 10 11 12 13 14} 0 1]
+
+test listrep-3.32 {
+    Replacement of elements at back with more elements in unshared spanned list
+    with insufficient total space reallocates with more room in the tail because
+    of realloc()
+} -body {
+    set l [lreplace [freeSpaceBoth 8 1 1] $end-1 $end 10 11 12 13 14]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 2 3 4 5 10 11 12 13 14} 1 10]
+
+test listrep-3.33 {
+    Replacement of elements in the middle in an unshared spanned list with
+    the same number of elements - lreplace version
+} -body {
+    set l [lreplace [freeSpaceBoth] $two $four 10 11 12]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 10 11 12 5 6 7} 3 3]
+
+test listrep-3.33.1 {
+    Replacement of elements in the middle in an unshared spanned list with
+    the same number of elements - lset version
+} -body {
+    set l [freeSpaceBoth]
+    lset l $two 10
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 10 3 4 5 6 7} 3 3]
+
+test listrep-3.34 {
+    Replacement of elements in an unshared spanned list with fewer elements
+    in the front half moves the front (smaller) segment
+} -body {
+    set l [lreplace [freeSpaceBoth] $two $four 10 11]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 10 11 5 6 7} 4 3]
+
+test listrep-3.35 {
+    Replacement of elements in an unshared spanned list with fewer elements
+    in the back half moves the tail (smaller) segment
+} -body {
+    set l [lreplace [freeSpaceBoth] $end-2 $end-1 10]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 2 3 4 10 7} 3 4]
+
+test listrep-3.36 {
+    Replacement of elements in an unshared spanned list with more elements
+    when both front and back have room should move the smaller segment
+    (front case)
+} -body {
+    set l [lreplace [freeSpaceBoth] $one $two 8 9 10]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 8 9 10 3 4 5 6 7} 2 3]
+
+test listrep-3.37 {
+    Replacement of elements in an unshared spanned list with more elements
+    when both front and back have room should move the smaller segment
+    (back case)
+} -body {
+    set l [lreplace [freeSpaceBoth] $end-2 $end-1 8 9 10]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 2 3 4 8 9 10 7} 3 2]
+
+test listrep-3.38 {
+    Replacement of elements in an unshared spanned list with more elements
+    when only front has room
+} -body {
+    set l [lreplace [freeSpaceBoth 8 3 1] $end-1 $end-1 8 9 10]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 1 2 3 4 5 8 9 10 7} 1 1]
+
+test listrep-3.39 {
+    Replacement of elements in an unshared spanned list with more elements
+    when only back has room
+} -body {
+    set l [lreplace [freeSpaceBoth 8 1 3] $one $one 8 9 10]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 8 9 10 2 3 4 5 6 7} 1 1]
+
+test listrep-3.40 {
+    Replacement of elements in an unshared spanned list with more elements
+    when neither send has enough room by itself
+} -body {
+    set l [lreplace [freeSpaceBoth] $one $one 8 9 10 11 12]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 8 9 10 11 12 2 3 4 5 6 7} 1 1]
+
+test listrep-3.41 {
+    Replacement of elements in an unshared spanned list with more elements
+    when there is not enough free space results in new allocation. The back
+    end has more space because of realloc()
+} -body {
+    set l [lreplace [freeSpaceBoth 8 1 1] $one $one 8 9 10 11 12]
+    validate $l
+    list $l [leadSpace $l] [tailSpace $l]
+} -result [list {0 8 9 10 11 12 2 3 4 5 6 7} 1 11]
+
+#
+# 4.* - tests on shared spanned lists
+
+test listrep-4.1 {
+    Inserts in front of shared spanned list with used elements in lead space
+    creates new list rep with more lead than tail space - linsert version
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set l [linsert $spanl $zero -1]
+    validate $l
+    list $master $spanl $l [leadSpaceMore $l] [hasSpan $l] [repStoreRefCount $master] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 0 999] [irange 2 997] [list -1 {*}[irange 2 997]] 1 1 2 2 1]
+
+test listrep-4.1.1 {
+    Inserts in front of shared spanned list with used elements in lead space
+    creates new list rep with more lead than tail space - lreplace version
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set l [lreplace $spanl $zero -1 -2]
+    validate $l
+    list $master $spanl $l [leadSpaceMore $l] [hasSpan $l] [repStoreRefCount $master] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 0 999] [irange 2 997] [list -2 {*}[irange 2 997]] 1 1 2 2 1]
+
+test listrep-4.2 {
+    Inserts in front of shared spanned list with orphaned leading elements
+    allocate a new list rep with more lead than tail space - linsert version
+    TODO - ideally this should garbage collect the orphans and reuse the lead space
+    but that needs a "lprepend" command else the listrep operand is shared and hence
+    orphans cannot be freed
+} -constraints testlistrep -body {
+    set master [freeSpaceLead 1000 100]
+    set spanl [lrange $master $two $end-2]
+    unset master; # So elements at 0, 1 are not used
+    set l [linsert $spanl $zero -1]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [leadSpaceMore $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [list -1 {*}[irange 2 997]] 0 1 1 1 1]
+
+test listrep-4.2.1 {
+    Inserts in front of shared spanned list with orphaned leading elements
+    allocate a new list rep with more lead than tail space - lreplace version
+    TODO - ideally this should garbage collect the orphans and reuse the lead space
+    but that needs a "lprepend" command else the listrep operand is shared and hence
+    orphans cannot be freed
+} -constraints testlistrep -body {
+    set master [freeSpaceLead 1000 100]
+    set spanl [lrange $master $two $end-2]
+    unset master; # So elements at 0, 1 are not used
+    set l [lreplace $spanl $zero -1 -2]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [leadSpaceMore $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [list -2 {*}[irange 2 997]] 0 1 1 1 1]
+
+test listrep-4.3 {
+    Inserts in front of shared spanned list where span is at front of used
+    space reuses the same list store - linsert version
+} -constraints testlistrep -body {
+    set master [freeSpaceLead 1000 100]
+    set spanl [lrange $master $zero $end-2]
+    set l [linsert $spanl $zero -1]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [leadSpace $l] [tailSpace $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 0 997] [irange -1 997] 1 99 0 1 3 3]
+
+test listrep-4.3.1 {
+    Inserts in front of shared spanned list where span is at front of used
+    space reuses the same list store - lreplace version
+} -constraints testlistrep -body {
+    set master [freeSpaceLead 1000 100]
+    set spanl [lrange $master $zero $end-2]
+    set l [lreplace $spanl $zero -1 -1]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [leadSpace $l] [tailSpace $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 0 997] [irange -1 997] 1 99 0 1 3 3]
+
+test listrep-4.4 {
+    Inserts in front of shared spanned list where span is at front of used
+    space allocates new listrep if lead space insufficient even if total free space
+    is sufficient. New listrep should have more lead space than tail space.
+    - linsert version
+} -constraints testlistrep -body {
+    set master [freeSpaceBoth 1000 2]
+    set spanl [lrange $master $zero $end-2]
+    set l [linsert $spanl $zero -3 -2 -1]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [leadSpaceMore $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 0 997] [irange -3 997] 0 1 1 2 1]
+
+test listrep-4.4.1 {
+    Inserts in front of shared spanned list where span is at front of used
+    space allocates new listrep if lead space insufficient even if total free space
+    is sufficient. New listrep should have more lead space than tail space.
+    - lreplace version
+} -constraints testlistrep -body {
+    set master [freeSpaceBoth 1000 2]
+    set spanl [lrange $master $zero $end-2]
+    set l [lreplace $spanl $zero -1 -3 -2 -1]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [leadSpaceMore $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 0 997] [irange -3 997] 0 1 1 2 1]
+
+test listrep-4.5 {
+    Inserts in back of shared spanned list where span is at end of used space
+    still allocates a new listrep and trailing space is more than leading space
+    - linsert version
+} -constraints testlistrep -body {
+    set master [freeSpaceBoth 1000 2]
+    set spanl [lrange $master $two $end]
+    set l [linsert $spanl $end 1000]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [tailSpaceMore $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 999] [irange 2 1000] 0 1 1 2 1]
+
+test listrep-4.5.1 {
+    Inserts in back of shared spanned list where span is at end of used space
+    still allocates a new listrep and trailing space is more than leading space
+    - lreplace version
+} -constraints testlistrep -body {
+    set master [freeSpaceBoth 1000 2]
+    set spanl [lrange $master $two $end]
+    set l [lreplace $spanl $end+1 $end+1 1000]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [tailSpaceMore $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 999] [irange 2 1000] 0 1 1 2 1]
+
+test listrep-4.5.2 {
+    Inserts in back of shared spanned list where span is at end of used space
+    still allocates a new listrep and trailing space is more than leading space
+    - lappend version
+} -constraints testlistrep -body {
+    set master [freeSpaceBoth 1000 2]
+    set l [lrange $master $two $end]
+    lappend l 1000
+    validate $l
+    list $l [sameStore $master $l] [tailSpaceMore $l] [hasSpan $l] [repStoreRefCount $l]
+} -result [list  [irange 2 1000] 0 1 1 1]
+
+test listrep-4.5.3 {
+    Inserts in back of shared spanned list where span is at end of used space
+    still allocates a new listrep and trailing space is more than leading space
+    - lset version
+} -constraints testlistrep -body {
+    set master [freeSpaceBoth 1000 2]
+    set l [lrange $master $two $end]
+    lset l $end+1 1000
+    validate $l
+    list $l [sameStore $master $l] [tailSpaceMore $l] [hasSpan $l] [repStoreRefCount $l]
+} -result [list  [irange 2 1000] 0 1 1 1]
+
+
+test listrep-4.6 {
+    Inserts in middle of shared spanned list allocates a new listrep with equal
+    lead and tail space - linsert version
+} -constraints testlistrep -body {
+    set master [freeSpaceBoth 1000 2]
+    set spanl [lrange $master $two $end-2]
+    set i 200
+    set l [linsert $spanl $i 1000]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [spaceEqual $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [concat [irange 2 201] 1000 [irange 202 997]] 0 1 1 2 1]
+
+test listrep-4.6.1 {
+    Inserts in middle of shared spanned list allocates a new listrep with equal
+    lead and tail space - lreplace version
+} -constraints testlistrep -body {
+    set master [freeSpaceBoth 1000 2]
+    set spanl [lrange $master $two $end-2]
+    set i 200
+    set l [lreplace $spanl $i -1 1000]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [spaceEqual $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [concat [irange 2 201] 1000 [irange 202 997]] 0 1 1 2 1]
+
+test listrep-4.7 {
+    Deletes from front of shared spanned list do not create a new allocation
+    - lreplace version
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set l [lreplace $spanl $zero $one]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [irange 4 997] 1 1 3 3]
+
+test listrep-4.7.1 {
+    Deletes from front of shared spanned list do not create a new allocation
+    - lremove version
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set l [lremove $spanl $zero $one]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [irange 4 997] 1 1 3 3]
+
+test listrep-4.7.2 {
+    Deletes from front of shared spanned list do not create a new allocation
+    - lrange version
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set l [lrange $spanl $two $end]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [irange 4 997] 1 1 3 3]
+
+test listrep-4.7.3 {
+    Deletes from front of shared spanned list do not create a new allocation
+    - lassign version
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set l [lassign $spanl e]
+    validate $l
+    list $e $spanl $l [sameStore $spanl $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list 2 [irange 2 997] [irange 3 997] 1 1 3 3]
+
+test listrep-4.7.4 {
+    Deletes from front of shared spanned list do not create a new allocation
+    - lpop version
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set l [lrange $master $two $end-2]
+    set e [lpop l $zero]
+    validate $l
+    list $e $l [sameStore $master $l] [hasSpan $l] [repStoreRefCount $l]
+} -result [list 2 [irange 3 997] 1 1 2]
+
+test listrep-4.8 {
+    Deletes from end of shared spanned list do not create a new allocation
+    - lreplace version
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set l [lreplace $spanl $end-1 $end]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [irange 2 995] 1 1 3 3]
+
+test listrep-4.8.1 {
+    Deletes from end of shared spanned list do not create a new allocation
+    - lremove version
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set l [lremove $spanl $end-1 $end]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [irange 2 995] 1 1 3 3]
+
+test listrep-4.8.2 {
+    Deletes from end of shared spanned list do not create a new allocation
+    - lrange version
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set l [lrange $spanl 0 $end-2]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [irange 2 995] 1 1 3 3]
+
+test listrep-4.8.3 {
+    Deletes from end of shared spanned list do not create a new allocation
+    - lpop version
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set l [lrange $master $two $end-2]
+    set e [lpop l]
+    validate $l
+    list $e $l [sameStore $master $l] [hasSpan $l] [repStoreRefCount $l]
+} -result [list 997 [irange 2 996] 1 1 2]
+
+test listrep-4.9 {
+    Deletes from middle of shared spanned list creates a new allocation with
+    equal free space at front and back - lreplace version
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set i 500
+    set l [lreplace $spanl $i $i]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [hasSpan $l] [spaceEqual $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [concat [irange 2 501] [irange 503 997]] 0 1 1 2 1]
+
+test listrep-4.9.1 {
+    Deletes from middle of shared spanned list creates a new allocation with
+    equal free space at front and back - lremove version
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set i 500
+    set l [lremove $spanl $i $i]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [hasSpan $l] [spaceEqual $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [concat [irange 2 501] [irange 503 997]] 0 1 1 2 1]
+
+test listrep-4.9.2 {
+    Deletes from middle of shared spanned list creates a new allocation with
+    equal free space at front and back - lpop version
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set l [lrange $master $two $end-2]
+    set i 500
+    set e [lpop l $i]
+    validate $l
+    list $e $l [sameStore $master $l] [hasSpan $l] [spaceEqual $l] [repStoreRefCount $l]
+} -result [list 502 [concat [irange 2 501] [irange 503 997]] 0 1 1 1]
+
+test listrep-4.10 {
+    Replacements with same number of elements at front of shared spanned list
+    create a new allocation with more space in front - lreplace version
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set l [lreplace $spanl $zero $one -2 -1]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [leadSpaceMore $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [concat {-2 -1} [irange 4 997]] 0 1 1 2 1]
+
+test listrep-4.10.1 {
+    Replacements with same number of elements at front of shared spanned list
+    create a new allocation with exact size
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set l [lrange $master $two $end-2]
+    lset l $zero -1
+    validate $l
+    list $l [sameStore $master $l] [hasSpan $l] [repStoreRefCount $l]
+} -result [list [concat {-1} [irange 3 997]] 0 0 1]
+
+test listrep-4.11 {
+    Replacements with fewer elements at front of shared spanned list
+    create a new allocation with more space in front
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set l [lreplace $spanl $zero $one -1]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [leadSpaceMore $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [concat {-1} [irange 4 997]] 0 1 1 2 1]
+
+test listrep-4.12 {
+    Replacements with more elements at front of shared spanned list
+    create a new allocation with more space in front
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set l [lreplace $spanl $zero $one -3 -2 -1]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [leadSpaceMore $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [concat {-3 -2 -1} [irange 4 997]] 0 1 1 2 1]
+
+test listrep-4.13 {
+    Replacements with same number of elements at back of shared spanned list
+    create a new allocation with more space in back - lreplace version
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set l [lreplace $spanl $end-1 $end 1000 1001]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [tailSpaceMore $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [concat [irange 2 995] {1000 1001}] 0 1 1 2 1]
+
+test listrep-4.13.1 {
+    Replacements with same number of elements at back of shared spanned list
+    create a new exact allocation with no span - lset version
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set l [lrange $master $two $end-2]
+    lset l $end 1000
+    validate $l
+    list $l [sameStore $master $l] [tailSpace $l] [hasSpan $l] [repStoreRefCount $l]
+} -result [list [concat [irange 2 996] {1000}] 0 0 0 1]
+
+test listrep-4.14 {
+    Replacements with fewer elements at back of shared spanned list
+    create a new allocation with more space in back
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set l [lreplace $spanl $end-1 $end 1000]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [tailSpaceMore $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [concat [irange 2 995] {1000}] 0 1 1 2 1]
+
+test listrep-4.15 {
+    Replacements with more elements at back of shared spanned list
+    create a new allocation with more space in back
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set l [lreplace $spanl $end-1 $end 1000 1001 1002]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [tailSpaceMore $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [concat [irange 2 995] {1000 1001 1002}] 0 1 1 2 1]
+
+test listrep-4.16 {
+    Replacements with same number of elements in middle of shared spanned list
+    create a new allocation with equal lead and tail sapce
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set l [lreplace $spanl $one $two -2 -1]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [spaceEqual $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [concat {2 -2 -1} [irange 5 997]] 0 1 1 2 1]
+
+test listrep-4.16.1 {
+    Replacements with same number of elements in middle of shared spanned list
+    create a new exact allocation - lset version
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set l [lrange $master $two $end-2]
+    lset l $one -2
+    validate $l
+    list $l [sameStore $master $l] [hasSpan $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [concat {2 -2} [irange 4 997]] 0 0 0 1]
+
+test listrep-4.17 {
+    Replacements with fewer elements in middle of shared spanned list
+    create a new allocation with equal lead and tail sapce
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set l [lreplace $spanl $end-2 $end-1 1000]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [spaceEqual $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [concat [irange 2 994] {1000 997}] 0 1 1 2 1]
+
+test listrep-4.18 {
+    Replacements with more elements in middle of shared spanned list
+    create a new allocation with equal lead and tail sapce
+} -constraints testlistrep -body {
+    set master [freeSpaceNone 1000]
+    set spanl [lrange $master $two $end-2]
+    set l [lreplace $spanl $end-2 $end-1 1000 1001 1002]
+    validate $l
+    list $spanl $l [sameStore $spanl $l] [spaceEqual $l] [hasSpan $l] [repStoreRefCount $spanl] [repStoreRefCount $l]
+} -result [list [irange 2 997] [concat [irange 2 994] {1000 1001 1002 997}] 0 1 1 2 1]
+
+# 5.* - tests on shared Tcl_Obj
+# Tests when Tcl_Obj is shared but listrep is not. This is to ensure that
+# checks for shared values check the Tcl_Obj reference counts in addition to
+# the list internal representation reference counts. Probably some or all
+# cases are already covered elsewhere but easier to just test than look.
+test listrep-5.1 {
+    Verify that operation on a shared Tcl_Obj with a single-ref, spanless
+    list representation only modifies the target object - lappend version
+} -constraints testlistrep -body {
+    set l [freeSpaceNone]
+    set l2 $l
+    set same [sameStore $l $l2]
+    lappend l 8
+    list $same $l $l2 [sameStore $l $l2]
+} -result [list 1 [irange 0 8] [irange 0 7] 0]
+
+test listrep-5.1.1 {
+    Verify that operation on a shared Tcl_Obj with a single-ref, spanless
+    list representation only modifies the target object - lset version
+} -constraints testlistrep -body {
+    set l [freeSpaceNone]
+    set l2 $l
+    set same [sameStore $l $l2]
+    lset l $end+1 8
+    list $same $l $l2 [sameStore $l $l2]
+} -result [list 1 [irange 0 8] [irange 0 7] 0]
+
+test listrep-5.1.2 {
+    Verify that operation on a shared Tcl_Obj with a single-ref, spanless
+    list representation only modifies the target object - lpop version
+} -constraints testlistrep -body {
+    set l [freeSpaceNone]
+    set l2 $l
+    set same [sameStore $l $l2]
+    lpop l
+    list $same $l $l2 [sameStore $l $l2] [hasSpan $l]
+} -result [list 1 [irange 0 6] [irange 0 7] 0 0]
+
+test listrep-5.2 {
+    Verify that operation on a shared Tcl_Obj with a single-ref, spanned
+    list representation only modifies the target object - lappend version
+} -constraints testlistrep -body {
+    set l [freeSpaceBoth 1000 10 10]
+    set l2 $l
+    set same [sameStore $l $l2]
+    lappend l 1000
+    list $same $l $l2 [sameStore $l $l2] [hasSpan $l] [hasSpan $l2]
+} -result [list 1 [irange 0 1000] [irange 0 999] 0 1 1]
+
+test listrep-5.2.1 {
+    Verify that operation on a shared Tcl_Obj with a single-ref, spanned
+    list representation only modifies the target object - lset version
+} -constraints testlistrep -body {
+    set l [freeSpaceBoth 1000 10 10]
+    set l2 $l
+    set same [sameStore $l $l2]
+    lset l $end+1 1000
+    list $same $l $l2 [sameStore $l $l2] [hasSpan $l] [hasSpan $l2]
+} -result [list 1 [irange 0 1000] [irange 0 999] 0 1 1]
+
+test listrep-5.2.2 {
+    Verify that operation on a shared Tcl_Obj with a single-ref, spanned
+    list representation only modifies the target object - lpop version
+} -constraints testlistrep -body {
+    set l [freeSpaceNone 1000]
+    set l2 $l
+    set same [sameStore $l $l2]
+    lpop l
+    list $same $l $l2 [sameStore $l $l2] [hasSpan $l] [hasSpan $l2]
+} -result [list 1 [irange 0 998] [irange 0 999] 1 1 0]
+
+#
+# 6.* - tests when lists contain zombies.
+# The list implementation does lazy freeing in some cases so the list store
+# contain Tcl_Obj's that are not actually referenced by any list (zombies).
+# These are to be freed next time the list store is modified by a list
+# operation as long as it is no longer shared.
+test listrep-6.1 {
+    Verify that zombies are freed up - linsert at front
+} -constraints testlistrep -body {
+    set l [zombieSample 200 10 10]
+    set addr [storeAddress $l]
+    # set l {} is for reference counts to drop to 1
+    set l [linsert $l[set l {}] $zero -1]
+    list $l [expr {$addr == [storeAddress $l]}] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [list -1 {*}[irange 10 209]] 1 9 10 1]
+
+test listrep-6.1.1 {
+    Verify that zombies are freed up - linsert in middle
+} -constraints testlistrep -body {
+    set l [zombieSample 200 10 10]
+    set addr [storeAddress $l]
+    # set l {} is for reference counts to drop to 1
+    set l [linsert $l[set l {}] $one -1]
+    list $l [expr {$addr == [storeAddress $l]}] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [list 10 -1 {*}[irange 11 209]] 1 9 10 1]
+
+test listrep-6.1.2 {
+    Verify that zombies are freed up - linsert at end
+} -constraints testlistrep -body {
+    set l [zombieSample 200 10 10]
+    set addr [storeAddress $l]
+    # set l {} is for reference counts to drop to 1
+    set l [linsert $l[set l {}] $end 210]
+    list $l [expr {$addr == [storeAddress $l]}] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange 10 210] 1 10 9 1]
+
+test listrep-6.2 {
+    Verify that zombies are freed up - lrange version (whole)
+} -constraints testlistrep -body {
+    set l [zombieSample 200 10 10]
+    set addr [storeAddress $l]
+    # set l {} is for reference counts to drop to 1
+    set l [lrange $l[set l {}] $zero $end]
+    list $l [expr {$addr == [storeAddress $l]}] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange 10 209] 1 10 10 1]
+
+test listrep-6.2.1 {
+    Verify that zombies are freed up - lrange version (subrange)
+} -constraints testlistrep -body {
+    set l [zombieSample 200 10 10]
+    set addr [storeAddress $l]
+    # set l {} is for reference counts to drop to 1
+    set l [lrange $l[set l {}] $one $end-1]
+    list $l [expr {$addr == [storeAddress $l]}] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange 11 208] 1 11 11 1]
+
+test listrep-6.3 {
+    Verify that zombies are freed up - lassign version
+} -constraints testlistrep -body {
+    set l [zombieSample 200 10 10]
+    set addr [storeAddress $l]
+    # set l {} is for reference counts to drop to 1
+    set l [lassign $l[set l {}] e]
+    list $e $l [expr {$addr == [storeAddress $l]}] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 10 [irange 11 209] 1 11 10 1]
+
+test listrep-6.4 {
+    Verify that zombies are freed up - lremove version (front)
+} -constraints testlistrep -body {
+    set l [zombieSample 200 10 10]
+    set addr [storeAddress $l]
+    # set l {} is for reference counts to drop to 1
+    set l [lremove $l[set l {}] $zero]
+    list $l [expr {$addr == [storeAddress $l]}] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange 11 209] 1 11 10 1]
+
+test listrep-6.4.1 {
+    Verify that zombies are freed up - lremove version (back)
+} -constraints testlistrep -body {
+    set l [zombieSample 200 10 10]
+    set addr [storeAddress $l]
+    # set l {} is for reference counts to drop to 1
+    set l [lremove $l[set l {}] $end]
+    list $l [expr {$addr == [storeAddress $l]}] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange 10 208] 1 10 11 1]
+
+test listrep-6.5 {
+    Verify that zombies are freed up - lreplace at front
+} -constraints testlistrep -body {
+    set l [zombieSample 200 10 10]
+    set addr [storeAddress $l]
+    # set l {} is for reference counts to drop to 1
+    set l [lreplace $l[set l {}] $zero $one -3 -2 -1]
+    list $l [expr {$addr == [storeAddress $l]}] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [list -3 -2 -1 {*}[irange 12 209]] 1 9 10 1]
+
+test listrep-6.5.1 {
+    Verify that zombies are freed up - lreplace at back
+} -constraints testlistrep -body {
+    set l [zombieSample 200 10 10]
+    set addr [storeAddress $l]
+    # set l {} is for reference counts to drop to 1
+    set l [lreplace $l[set l {}] $end-1 $end -1 -2 -3]
+    list $l [expr {$addr == [storeAddress $l]}] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [list {*}[irange 10 207] -1 -2 -3] 1 10 9 1]
+
+test listrep-6.6 {
+    Verify that zombies are freed up - lappend
+} -constraints testlistrep -body {
+    set l [zombieSample 200 10 10]
+    set addr [storeAddress $l]
+    lappend l 210
+    list $l [expr {$addr == [storeAddress $l]}] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange 10 210] 1 10 9 1]
+
+test listrep-6.7 {
+    Verify that zombies are freed up - lpop version (front)
+} -constraints testlistrep -body {
+    set l [zombieSample 200 10 10]
+    set addr [storeAddress $l]
+    set e [lpop l $zero]
+    list $e $l [expr {$addr == [storeAddress $l]}] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 10 [irange 11 209] 1 11 10 1]
+
+test listrep-6.7.1 {
+    Verify that zombies are freed up - lpop version (back)
+} -constraints testlistrep -body {
+    set l [zombieSample 200 10 10]
+    set addr [storeAddress $l]
+    set e [lpop l]
+    list $e $l [expr {$addr == [storeAddress $l]}] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list 209 [irange 10 208] 1 10 11 1]
+
+test listrep-6.8 {
+    Verify that zombies are freed up - lset version
+} -constraints testlistrep -body {
+    set l [zombieSample 200 10 10]
+    set addr [storeAddress $l]
+    lset l $zero -1
+    list $l [expr {$addr == [storeAddress $l]}] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [list -1 {*}[irange 11 209]] 1 10 10 1]
+
+test listrep-6.8.1 {
+    Verify that zombies are freed up - lset version (back)
+} -constraints testlistrep -body {
+    set l [zombieSample 200 10 10]
+    set addr [storeAddress $l]
+    lset l $end+1 210
+    list $l [expr {$addr == [storeAddress $l]}] [leadSpace $l] [tailSpace $l] [repStoreRefCount $l]
+} -result [list [irange 10 210] 1 10 9 1]
+
+
+# All done
+::tcltest::cleanupTests
+
+return
diff --git a/tests/oo.test b/tests/oo.test
index 105c492..ff67cc1 100644
--- a/tests/oo.test
+++ b/tests/oo.test
@@ -7,7 +7,7 @@
 # See the file "license.terms" for information on usage and redistribution of
 # this file, and for a DISCLAIMER OF ALL WARRANTIES.
 
-package require tcl::oo 1.2.0
+package require tcl::oo 1.3.0
 if {"::tcltest" ni [namespace children]} {
     package require tcltest 2.5
     namespace import -force ::tcltest::*
diff --git a/tests/ooNext2.test b/tests/ooNext2.test
index ce4acdf..746f9a5 100644
--- a/tests/ooNext2.test
+++ b/tests/ooNext2.test
@@ -7,7 +7,7 @@
 # See the file "license.terms" for information on usage and redistribution of
 # this file, and for a DISCLAIMER OF ALL WARRANTIES.
 
-package require tcl::oo 1.2.0
+package require tcl::oo 1.3.0
 if {"::tcltest" ni [namespace children]} {
     package require tcltest 2.5
     namespace import -force ::tcltest::*
diff --git a/tests/ooUtil.test b/tests/ooUtil.test
index 4db971e..c8be9c8 100644
--- a/tests/ooUtil.test
+++ b/tests/ooUtil.test
@@ -9,7 +9,7 @@
 # See the file "license.terms" for information on usage and redistribution of
 # this file, and for a DISCLAIMER OF ALL WARRANTIES.
 
-package require tcl::oo 1.2.0
+package require tcl::oo 1.3.0
 if {"::tcltest" ni [namespace children]} {
     package require tcltest 2.5
     namespace import -force ::tcltest::*
diff --git a/tests/winConsole.test b/tests/winConsole.test
index 0daf54c..821a143 100644
--- a/tests/winConsole.test
+++ b/tests/winConsole.test
@@ -52,13 +52,21 @@ test console-input-1.0 {Console blocking gets} -constraints {win interactive} -b
 
 test console-input-1.1 {Console file channel: non-blocking gets} -constraints {
     win interactive
+} -setup {
+    unset -nocomplain result
+    unset -nocomplain result2
 } -body {
     set oldmode [fconfigure stdin]
 
     prompt "Type \"abc\" and hit Enter: "
     fileevent stdin readable {
 	if {[gets stdin line] >= 0} {
-	    set result $line
+	    lappend result2 $line
+            if {[llength $result2] > 1} {
+                set result $result2
+            } else {
+                prompt "Type \"def\" and hit Enter: "
+            }
 	} elseif {[eof stdin]} {
 	    set result "gets failed"
 	}
@@ -66,7 +74,6 @@ test console-input-1.1 {Console file channel: non-blocking gets} -constraints {
 
     fconfigure stdin -blocking 0 -buffering line
 
-    set result {}
     vwait result
 
     #cleanup the fileevent
@@ -74,7 +81,35 @@ test console-input-1.1 {Console file channel: non-blocking gets} -constraints {
     fconfigure stdin {*}$oldmode
     set result
 
-} -result abc
+} -result {abc def}
+
+test console-input-1.1.1 {Bug baa51423c28a: Console file channel: fileevent with blocking gets} -constraints {
+    win interactive
+} -setup {
+    unset -nocomplain result
+    unset -nocomplain result2
+} -body {
+    prompt "Type \"abc\" and hit Enter: "
+    fileevent stdin readable {
+	if {[gets stdin line] >= 0} {
+	    lappend result2 $line
+            if {[llength $result2] > 1} {
+                set result $result2
+            } else {
+                prompt "Type \"def\" and hit Enter: "
+            }
+	} elseif {[eof stdin]} {
+	    set result "gets failed"
+	}
+    }
+
+    vwait result
+
+    #cleanup the fileevent
+    fileevent stdin readable {}
+    set result
+
+} -result {abc def}
 
 test console-input-2.0 {Console blocking read} -constraints {win interactive} -setup {
     set oldmode [fconfigure stdin]
@@ -94,6 +129,7 @@ test console-input-2.1 {Console file channel: non-blocking read} -constraints {
     set oldmode [fconfigure stdin]
 } -cleanup {
     fconfigure stdin {*}$oldmode
+    puts ""; # Because CRLF also would not have been echoed
 } -body {
     set input ""
     fconfigure stdin -blocking 0 -buffering line -inputmode raw
@@ -262,10 +298,10 @@ test console-fconfigure-set-1.1 {
     fconfigure stdin -inputmode normal
     lappend result [yesno "\nWere the characters echoed?"]
 
-    prompt "\nType the keys \"c\", Ctrl-H, \"d\" and hit Enter. You should see characters echoed: "
+    prompt "Type the keys \"c\", Ctrl-H, \"d\" and hit Enter. You should see characters echoed: "
     lappend result [gets stdin]
     lappend result [fconfigure stdin -inputmode]
-    lappend result [yesno "\nWere the characters echoed (c replaced by d)?"]
+    lappend result [yesno "Were the characters echoed (c replaced by d)?"]
 
     set result
 } -result [list a\x08b raw 0 d normal 1]
diff --git a/unix/tclUnixSock.c b/unix/tclUnixSock.c
index d2068c3..217d5ce 100644
--- a/unix/tclUnixSock.c
+++ b/unix/tclUnixSock.c
@@ -53,11 +53,9 @@ typedef struct TcpFdList {
 
 struct TcpState {
     Tcl_Channel channel;	/* Channel associated with this file. */
-    int testFlags;              /* bit field for tests. Is set by testsocket
-                                 * test procedure */
-    TcpFdList fds;		/* The file descriptors of the sockets. */
     int flags;			/* ORed combination of the bitfields defined
 				 * below. */
+    TcpFdList fds;		/* The file descriptors of the sockets. */
     int interest;		/* Event types of interest */
 
     /*
@@ -95,12 +93,7 @@ struct TcpState {
 					 * still pending */
 #define TCP_ASYNC_FAILED	(1<<5)	/* An async connect finally failed */
 
-/*
- * These bits may be ORed together into the "testFlags" field of a TcpState
- * structure.
- */
-
-#define TCP_ASYNC_TEST_MODE	(1<<0)	/* Async testing activated.  Do not
+#define TCP_ASYNC_TEST_MODE	(1<<8)	/* Async testing activated.  Do not
 					 * automatically continue connection
 					 * process. */
 
@@ -434,7 +427,7 @@ TcpBlockModeProc(
  *
  * Side effects:
  *	Processes socket events off the system queue. May process
- *	asynchroneous connects.
+ *	asynchronous connects.
  *
  *----------------------------------------------------------------------
  */
@@ -471,7 +464,7 @@ WaitForConnect(
      *   (errorCodePtr != NULL && !GOT_BITS(flags, TCP_NONBLOCKING))
      */
 
-    if (GOT_BITS(statePtr->testFlags, TCP_ASYNC_TEST_MODE)
+    if (GOT_BITS(statePtr->flags, TCP_ASYNC_TEST_MODE)
             && !(errorCodePtr != NULL
                     && !GOT_BITS(statePtr->flags, TCP_NONBLOCKING))) {
 	*errorCodePtr = EWOULDBLOCK;
@@ -880,8 +873,8 @@ TcpGetOptionProc(
 
     if ((len > 1) && (optionName[1] == 'c') &&
 	    (strncmp(optionName, "-connecting", len) == 0)) {
-        Tcl_DStringAppend(dsPtr,
-                GOT_BITS(statePtr->flags, TCP_ASYNC_CONNECT) ? "1" : "0", TCL_INDEX_NONE);
+	Tcl_DStringAppend(dsPtr,
+		GOT_BITS(statePtr->flags, TCP_ASYNC_CONNECT) ? "1" : "0", TCL_INDEX_NONE);
         return TCL_OK;
     }
 
@@ -1351,7 +1344,7 @@ TcpConnect(
         }
 
         /*
-         * We need to forward the writable event that brought us here, bcasue
+         * We need to forward the writable event that brought us here, because
          * upon reading of getsockopt(SO_ERROR), at least some OSes clear the
          * writable state from the socket, and so a subsequent select() on
          * behalf of a script level [fileevent] would not fire. It doesn't
diff --git a/unix/tclooConfig.sh b/unix/tclooConfig.sh
index 4c2068c..a400b5b 100644
--- a/unix/tclooConfig.sh
+++ b/unix/tclooConfig.sh
@@ -16,4 +16,4 @@ TCLOO_STUB_LIB_SPEC=""
 TCLOO_INCLUDE_SPEC=""
 TCLOO_PRIVATE_INCLUDE_SPEC=""
 TCLOO_CFLAGS=""
-TCLOO_VERSION=1.2.0
+TCLOO_VERSION=1.3
diff --git a/win/tclWinConsole.c b/win/tclWinConsole.c
index 23652de..753a572 100644
--- a/win/tclWinConsole.c
+++ b/win/tclWinConsole.c
@@ -19,8 +19,8 @@
 #include <ctype.h>
 
 /*
- * A general note on the design: The console channel driver differs from most
- * other drivers in the following respects:
+ * A general note on the design: The console channel driver differs from
+ * most other drivers in the following respects:
  *
  * - There can be at most 3 console handles at any time since Windows does
  *   support allocation of more than one console (with three handles
@@ -35,9 +35,10 @@
  *   std* channels are shared amongst threads which means there can be
  *   multiple Tcl channels corresponding to a single console handle.
  *
- * - Even with multiple threads, more than one file event handler is unlikely.
- *   It does not make sense for multiple threads to register handlers for
- *   stdin because the input would be randomly fragmented amongst the threads.
+ * - Even with multiple threads, more than one file event handler is
+ * unlikely. It does not make sense for multiple threads to register
+ * handlers for stdin because the input would be randomly fragmented amongst
+ * the threads.
  *
  * Various design factors are driven by the above, e.g. use of lists instead
  * of hash tables (at most 3 console handles) and use of global instead of
@@ -55,9 +56,9 @@
  * because an interpreter may (for example) turn off echo for passwords and
  * the read ahead would come in the way of that.
  *
- * If multiple threads are reading from stdin, the input is sprayed in random
- * fashion. This is not good application design and hence no plan to address
- * this (not clear what should be done even in theory)
+ * If multiple threads are reading from stdin, the input is sprayed in
+ * random fashion. This is not good application design and hence no plan to
+ * address this (not clear what should be done even in theory)
  *
  * For output, we do not restrict all output to the console writer threads.
  * See ConsoleOutputProc for the conditions.
@@ -152,7 +153,7 @@ typedef struct ConsoleHandleInfo {
  * only from the thread owning channel EXCEPT when a console traverses it
  * looking for a channel that is watching for events on the console. Even
  * in that case, no locking is required because that access is only under
- * the consoleLock lock which prevents the channel from being removed from
+ * the gConsoleLock lock which prevents the channel from being removed from
  * the gWatchingChannelList which in turn means it will not be deallocated
  * from under the console thread. Access to individual fields does not need
  * to be controlled because
@@ -861,21 +862,33 @@ ConsoleCheckProc(
 	handleInfoPtr = FindConsoleInfo(chanInfoPtr);
 	/* Pointer is safe to access as we are holding gConsoleLock */
 
-	if (handleInfoPtr != NULL) {
-	    AcquireSRWLockShared(&handleInfoPtr->lock);
-	    /* Rememebr channel is read or write, never both */
-	    if (chanInfoPtr->watchMask & TCL_READABLE) {
-		if (RingBufferLength(&handleInfoPtr->buffer) > 0
-		    || handleInfoPtr->lastError != ERROR_SUCCESS) {
-		    needEvent = 1; /* Input data available or error/EOF */
-		}
-	    } else if (chanInfoPtr->watchMask & TCL_WRITABLE) {
-		if (RingBufferHasFreeSpace(&handleInfoPtr->buffer)) {
-		    needEvent = 1; /* Output space available */
-		}
+	if (handleInfoPtr == NULL) {
+	    /* Stale event */
+	    continue;
+	}
+
+	needEvent = 0;
+	AcquireSRWLockShared(&handleInfoPtr->lock);
+	/* Rememeber channel is read or write, never both */
+	if (chanInfoPtr->watchMask & TCL_READABLE) {
+	    if (RingBufferLength(&handleInfoPtr->buffer) > 0
+		|| handleInfoPtr->lastError != ERROR_SUCCESS) {
+		needEvent = 1; /* Input data available or error/EOF */
+	    }
+	    /*
+	     * TCL_READABLE watch means someone is looking out for data being
+	     * available, let reader thread know. Note channel need not be
+	     * ASYNC! (Bug [baa51423c2])
+	     */
+	    handleInfoPtr->flags |= CONSOLE_DATA_AWAITED;
+	    WakeConditionVariable(&handleInfoPtr->consoleThreadCV);
+	}
+	else if (chanInfoPtr->watchMask & TCL_WRITABLE) {
+	    if (RingBufferHasFreeSpace(&handleInfoPtr->buffer)) {
+		needEvent = 1; /* Output space available */
 	    }
-	    ReleaseSRWLockShared(&handleInfoPtr->lock);
 	}
+	ReleaseSRWLockShared(&handleInfoPtr->lock);
 
 	if (needEvent) {
 	    ConsoleEvent *evPtr = (ConsoleEvent *)ckalloc(sizeof(ConsoleEvent));
@@ -1103,12 +1116,6 @@ ConsoleInputProc(
 	 * buffered data, we will pass it up.
 	 */
 	if (numRead != 0) {
-	    /* If console thread was blocked, awaken it */
-	    if (chanInfoPtr->flags & CONSOLE_ASYNC) {
-		/* Async channels always want read ahead */
-		handleInfoPtr->flags |= CONSOLE_DATA_AWAITED;
-		WakeConditionVariable(&handleInfoPtr->consoleThreadCV);
-	    }
 	    break;
 	}
 	/*
@@ -1199,7 +1206,9 @@ ConsoleInputProc(
 	/* Lock is reacquired, loop back to try again */
     }
 
-    if (chanInfoPtr->flags & CONSOLE_ASYNC) {
+    /* We read data. Ask for more if either async or watching for reads */
+    if ((chanInfoPtr->flags & CONSOLE_ASYNC)
+	|| (chanInfoPtr->watchMask & TCL_READABLE)) {
 	handleInfoPtr->flags |= CONSOLE_DATA_AWAITED;
 	WakeConditionVariable(&handleInfoPtr->consoleThreadCV);
     }
@@ -1333,7 +1342,7 @@ ConsoleOutputProc(
 	    }
 	}
 
-	/* Lock is reacquired. Continue loop */
+	/* Lock must have been reacquired before continuing loop */
     }
     WakeConditionVariable(&handleInfoPtr->consoleThreadCV);
     ReleaseSRWLockExclusive(&handleInfoPtr->lock);
@@ -1499,8 +1508,10 @@ ConsoleWatchProc(
 	    ConsoleHandleInfo *handleInfoPtr;
 	    handleInfoPtr = FindConsoleInfo(chanInfoPtr);
 	    if (handleInfoPtr) {
+		AcquireSRWLockExclusive(&handleInfoPtr->lock);
 		handleInfoPtr->flags |= CONSOLE_DATA_AWAITED;
 		WakeConditionVariable(&handleInfoPtr->consoleThreadCV);
+		ReleaseSRWLockExclusive(&handleInfoPtr->lock);
 	    }
 	    ReleaseSRWLockExclusive(&gConsoleLock);
 	}
@@ -1508,6 +1519,7 @@ ConsoleWatchProc(
     } else if (oldMask) {
 	/* Remove from list of watched channels */
 
+	AcquireSRWLockExclusive(&gConsoleLock);
 	for (nextPtrPtr = &gWatchingChannelList, ptr = *nextPtrPtr;
 		ptr != NULL;
 		nextPtrPtr = &ptr->nextWatchingChannelPtr, ptr = *nextPtrPtr) {
@@ -1516,6 +1528,7 @@ ConsoleWatchProc(
 		break;
 	    }
 	}
+	ReleaseSRWLockExclusive(&gConsoleLock);
     }
 }
 
@@ -1571,7 +1584,7 @@ ConsoleGetHandleProc(
  static int
  ConsoleDataAvailable (HANDLE consoleHandle)
 {
-    INPUT_RECORD input[5];
+    INPUT_RECORD input[10];
     DWORD count;
     DWORD i;
 
@@ -1583,11 +1596,17 @@ ConsoleGetHandleProc(
 	== FALSE) {
 	return -1;
     }
+    /*
+     * Even if windows size and mouse events are disabled, can still have
+     * events other than keyboard, like focus events. Look for at least one
+     * keydown event because a trailing LF keyup is always present from the
+     * last input. However, if our buffer is full, assume there is a key
+     * down somewhere in the unread buffer. I suppose we could expand the
+     * buffer but not worth...
+     */
+    if (count == (sizeof(input)/sizeof(input[0])))
+	return 1;
     for (i = 0; i < count; ++i) {
-	/*
-	 * Event must be a keydown because a trailing LF keyup event is always
-	 * present for line based input.
-	 */
 	if (input[i].EventType == KEY_EVENT
 	    && input[i].Event.KeyEvent.bKeyDown) {
 	    return 1;
@@ -1984,6 +2003,7 @@ AllocateConsoleHandleInfo(
 
 
     handleInfoPtr = (ConsoleHandleInfo *)ckalloc(sizeof(*handleInfoPtr));
+    memset(handleInfoPtr, 0, sizeof(*handleInfoPtr));
     handleInfoPtr->console = consoleHandle;
     InitializeSRWLock(&handleInfoPtr->lock);
     InitializeConditionVariable(&handleInfoPtr->consoleThreadCV);
diff --git a/win/tclWinInit.c b/win/tclWinInit.c
index fdeb0aa..8fa176b 100644
--- a/win/tclWinInit.c
+++ b/win/tclWinInit.c
@@ -527,7 +527,14 @@ TclpSetVariables(
 	    Tcl_SetVar2(interp, "env", "HOME", Tcl_DStringValue(&ds),
 		    TCL_GLOBAL_ONLY);
 	} else {
-	    Tcl_SetVar2(interp, "env", "HOME", "c:\\", TCL_GLOBAL_ONLY);
+            /* None of HOME, HOMEDRIVE, HOMEPATH exists. Try USERPROFILE */
+            ptr = Tcl_GetVar2(interp, "env", "USERPROFILE", TCL_GLOBAL_ONLY);
+            if (ptr != NULL && ptr[0]) {
+                Tcl_SetVar2(interp, "env", "HOME", ptr, TCL_GLOBAL_ONLY);
+            } else {
+                /* Last resort */
+                Tcl_SetVar2(interp, "env", "HOME", "c:\\", TCL_GLOBAL_ONLY);
+            }
 	}
     }
 
diff --git a/win/tclWinSock.c b/win/tclWinSock.c
index e806423..f1a6a5e 100644
--- a/win/tclWinSock.c
+++ b/win/tclWinSock.c
@@ -125,11 +125,9 @@ typedef struct TcpFdList {
 
 struct TcpState {
     Tcl_Channel channel;	/* Channel associated with this socket. */
-    int testFlags;              /* bit field for tests. Is set by testsocket
-                                 * test procedure */
-    struct TcpFdList *sockets;	/* Windows SOCKET handle. */
     int flags;			/* Bit field comprised of the flags described
 				 * below. */
+    struct TcpFdList *sockets;	/* Windows SOCKET handle. */
     int watchEvents;		/* OR'ed combination of FD_READ, FD_WRITE,
 				 * FD_CLOSE, FD_ACCEPT and FD_CONNECT that
 				 * indicate which events are interesting. */
@@ -149,7 +147,7 @@ struct TcpState {
 				 * protected by semaphore */
     Tcl_TcpAcceptProc *acceptProc;
 				/* Proc to call on accept. */
-    ClientData acceptProcData;	/* The data for the accept proc. */
+    void *acceptProcData;	/* The data for the accept proc. */
 
     /*
      * Only needed for client sockets
@@ -186,12 +184,7 @@ struct TcpState {
 					 * still pending */
 #define TCP_ASYNC_FAILED	(1<<5)	/* An async connect finally failed */
 
-/*
- * These bits may be ORed together into the "testFlags" field of a TcpState
- * structure.
- */
-
-#define TCP_ASYNC_TEST_MODE	(1<<0)	/* Async testing activated.  Do not
+#define TCP_ASYNC_TEST_MODE	(1<<8)	/* Async testing activated.  Do not
 					 * automatically continue connection
 					 * process */
 
@@ -245,7 +238,7 @@ static int		TcpConnect(Tcl_Interp *interp,
 			    TcpState *state);
 static void		InitSockets(void);
 static TcpState *	NewSocketInfo(SOCKET socket);
-static void		SocketExitHandler(ClientData clientData);
+static void		SocketExitHandler(void *clientData);
 static LRESULT CALLBACK	SocketProc(HWND hwnd, UINT message, WPARAM wParam,
 			    LPARAM lParam);
 static int		SocketsEnabled(void);
@@ -256,7 +249,7 @@ static int		WaitForSocketEvent(TcpState *statePtr, int events,
 static void		AddSocketInfoFd(TcpState *statePtr,  SOCKET socket);
 static int		FindFDInList(TcpState *statePtr, SOCKET socket);
 static DWORD WINAPI	SocketThread(LPVOID arg);
-static void		TcpThreadActionProc(ClientData instanceData,
+static void		TcpThreadActionProc(void *instanceData,
 			    int action);
 
 static Tcl_EventCheckProc	SocketCheckProc;
@@ -392,8 +385,8 @@ InitializeHostName(
 	    Tcl_DStringSetLength(&inDs, 256);
 	    if (gethostname(Tcl_DStringValue(&inDs),
 		    Tcl_DStringLength(&inDs)) == 0) {
-		Tcl_ExternalToUtfDString(NULL, Tcl_DStringValue(&inDs), TCL_INDEX_NONE,
-			&ds);
+		Tcl_ExternalToUtfDString(NULL, Tcl_DStringValue(&inDs),
+			TCL_INDEX_NONE, &ds);
 	    }
 	    Tcl_DStringFree(&inDs);
 	}
@@ -466,7 +459,7 @@ TclpHasSockets(
     }
     if (interp != NULL) {
 	Tcl_SetObjResult(interp, Tcl_NewStringObj(
-		"sockets are not available on this system", -1));
+		"sockets are not available on this system", TCL_INDEX_NONE));
     }
     return TCL_ERROR;
 }
@@ -548,7 +541,7 @@ TclpFinalizeSockets(void)
 
 static int
 TcpBlockModeProc(
-    ClientData instanceData,	/* Socket state. */
+    void *instanceData,	/* Socket state. */
     int mode)			/* The mode to set. Can be one of
 				 * TCL_MODE_BLOCKING or
 				 * TCL_MODE_NONBLOCKING. */
@@ -558,7 +551,7 @@ TcpBlockModeProc(
     if (mode == TCL_MODE_NONBLOCKING) {
 	SET_BITS(statePtr->flags, TCP_NONBLOCKING);
     } else {
-        CLEAR_BITS(statePtr->flags, TCP_NONBLOCKING);
+	CLEAR_BITS(statePtr->flags, TCP_NONBLOCKING);
     }
     return 0;
 }
@@ -589,7 +582,7 @@ TcpBlockModeProc(
  *
  * Side effects:
  *	Processes socket events off the system queue. May process
- *	asynchroneous connect.
+ *	asynchronous connect.
  *
  *----------------------------------------------------------------------
  */
@@ -630,7 +623,7 @@ WaitForConnect(
      * - Call by the event queue (errorCodePtr == NULL)
      */
 
-    if (GOT_BITS(statePtr->testFlags, TCP_ASYNC_TEST_MODE)
+    if (GOT_BITS(statePtr->flags, TCP_ASYNC_TEST_MODE)
 	    && errorCodePtr != NULL
             && GOT_BITS(statePtr->flags, TCP_NONBLOCKING)) {
 	*errorCodePtr = EWOULDBLOCK;
@@ -656,13 +649,13 @@ WaitForConnect(
 	WaitForSingleObject(tsdPtr->socketListLock, INFINITE);
 
 	/*
-         * Check for connect event.
-         */
+	 * Check for connect event.
+	 */
 
 	if (GOT_BITS(statePtr->readyEvents, FD_CONNECT)) {
 	    /*
-             * Consume the connect event.
-             */
+	     * Consume the connect event.
+	     */
 
 	    CLEAR_BITS(statePtr->readyEvents, FD_CONNECT);
 
@@ -677,8 +670,8 @@ WaitForConnect(
 	    }
 
 	    /*
-             * Free list lock.
-             */
+	     * Free list lock.
+	     */
 
 	    SetEvent(tsdPtr->socketListLock);
 
@@ -690,8 +683,8 @@ WaitForConnect(
 	    result = TcpConnect(NULL, statePtr);
 
 	    /*
-             * Restore event service mode.
-             */
+	     * Restore event service mode.
+	     */
 
 	    (void) Tcl_SetServiceMode(oldMode);
 
@@ -779,7 +772,7 @@ WaitForConnect(
 
 static int
 TcpInputProc(
-    ClientData instanceData,	/* Socket state. */
+    void *instanceData,	/* Socket state. */
     char *buf,			/* Where to store data read. */
     int bufSize,		/* How much space is available in the
 				 * buffer? */
@@ -834,9 +827,9 @@ TcpInputProc(
 	SendSelectMessage(tsdPtr, UNSELECT, statePtr);
 
 	/*
-         * Single fd operation: this proc is only called for a connected
-         * socket.
-         */
+	 * Single fd operation: this proc is only called for a connected
+	 * socket.
+	 */
 
 	bytesRead = recv(statePtr->sockets->fd, buf, bufSize, 0);
 	CLEAR_BITS(statePtr->readyEvents, FD_READ);
@@ -881,7 +874,7 @@ TcpInputProc(
 	 */
 
 	if (GOT_BITS(statePtr->flags, TCP_NONBLOCKING)
-                || (error != WSAEWOULDBLOCK)) {
+	        || (error != WSAEWOULDBLOCK)) {
 	    Tcl_WinConvertError(error);
 	    *errorCodePtr = Tcl_GetErrno();
 	    bytesRead = -1;
@@ -923,7 +916,7 @@ TcpInputProc(
 
 static int
 TcpOutputProc(
-    ClientData instanceData,	/* Socket state. */
+    void *instanceData,	/* Socket state. */
     const char *buf,		/* The data buffer. */
     int toWrite,		/* How many bytes to write? */
     int *errorCodePtr)		/* Where to store error code. */
@@ -960,9 +953,9 @@ TcpOutputProc(
 	SendSelectMessage(tsdPtr, UNSELECT, statePtr);
 
 	/*
-         * Single fd operation: this proc is only called for a connected
-         * socket.
-         */
+	 * Single fd operation: this proc is only called for a connected
+	 * socket.
+	 */
 
 	written = send(statePtr->sockets->fd, buf, toWrite, 0);
 	if (written != SOCKET_ERROR) {
@@ -1038,7 +1031,7 @@ TcpOutputProc(
 
 static int
 TcpCloseProc(
-    ClientData instanceData,	/* The socket to close. */
+    void *instanceData,	/* The socket to close. */
     TCL_UNUSED(Tcl_Interp *))
 {
     TcpState *statePtr = (TcpState *)instanceData;
@@ -1088,16 +1081,16 @@ TcpCloseProc(
     if (tsdPtr->pendingTcpState != NULL
 	    && tsdPtr->pendingTcpState == statePtr) {
 	/*
-         * Get infoPtr lock, because this concerns the notifier thread.
-         */
+	 * Get infoPtr lock, because this concerns the notifier thread.
+	 */
 
 	WaitForSingleObject(tsdPtr->socketListLock, INFINITE);
 
 	tsdPtr->pendingTcpState = NULL;
 
 	/*
-         * Free list lock.
-         */
+	 * Free list lock.
+	 */
 
 	SetEvent(tsdPtr->socketListLock);
     }
@@ -1132,7 +1125,7 @@ TcpCloseProc(
 
 static int
 TcpClose2Proc(
-    ClientData instanceData,	/* The socket to close. */
+    void *instanceData,	/* The socket to close. */
     Tcl_Interp *interp,		/* For error reporting. */
     int flags)			/* Flags that indicate which side to close. */
 {
@@ -1182,7 +1175,7 @@ TcpClose2Proc(
 
 static int
 TcpSetOptionProc(
-    ClientData instanceData,	/* Socket state. */
+    void *instanceData,	/* Socket state. */
     Tcl_Interp *interp,		/* For error reporting - can be NULL. */
     const char *optionName,	/* Name of the option to set. */
     TCL_UNUSED(const char *) /*value*/)		/* New value for option. */
@@ -1287,7 +1280,7 @@ TcpSetOptionProc(
 
 static int
 TcpGetOptionProc(
-    ClientData instanceData,	/* Socket state. */
+    void *instanceData,	/* Socket state. */
     Tcl_Interp *interp,		/* For error reporting - can be NULL. */
     const char *optionName,	/* Name of the option to retrieve the value
 				 * for, or NULL to get all options and their
@@ -1323,7 +1316,7 @@ TcpGetOptionProc(
      * below.
      */
 
-    if (!GOT_BITS(statePtr->testFlags, TCP_ASYNC_TEST_MODE)) {
+    if (!GOT_BITS(statePtr->flags, TCP_ASYNC_TEST_MODE)) {
 	WaitForConnect(statePtr, NULL);
     }
 
@@ -1335,8 +1328,8 @@ TcpGetOptionProc(
     if ((len > 1) && (optionName[1] == 'e') &&
 	    (strncmp(optionName, "-error", len) == 0)) {
 	/*
-         * Do not return any errors if async connect is running.
-         */
+	 * Do not return any errors if async connect is running.
+	 */
 
 	if (!GOT_BITS(statePtr->flags, TCP_ASYNC_PENDING)) {
 	    if (GOT_BITS(statePtr->flags, TCP_ASYNC_FAILED)) {
@@ -1383,8 +1376,7 @@ TcpGetOptionProc(
 
 		if (err) {
 		    Tcl_WinConvertError(err);
-		    Tcl_DStringAppend(dsPtr, Tcl_ErrnoMsg(Tcl_GetErrno()),
-                            -1);
+		    Tcl_DStringAppend(dsPtr, Tcl_ErrnoMsg(Tcl_GetErrno()), -1);
 		}
 	    }
 	}
@@ -1400,7 +1392,7 @@ TcpGetOptionProc(
     }
 
     if (interp != NULL
-            && Tcl_GetVar2(interp, SUPPRESS_RDNS_VAR, NULL, 0) != NULL) {
+	    && Tcl_GetVar(interp, SUPPRESS_RDNS_VAR, 0) != NULL) {
 	reverseDNS = NI_NUMERICHOST;
     }
 
@@ -1421,7 +1413,7 @@ TcpGetOptionProc(
 		return TCL_OK;
 	    }
 	} else if (getpeername(sock, (LPSOCKADDR) &(peername.sa),
-                &size) == 0) {
+		&size) == 0) {
 	    /*
 	     * Peername fetch succeeded - output list
 	     */
@@ -1479,7 +1471,7 @@ TcpGetOptionProc(
 	     * In async connect output an empty string
 	     */
 
-            found = 1;
+	    found = 1;
 	} else {
 	    for (fds = statePtr->sockets; fds != NULL; fds = fds->next) {
 		sock = fds->fd;
@@ -1609,7 +1601,7 @@ TcpGetOptionProc(
 
 static void
 TcpWatchProc(
-    ClientData instanceData,	/* The socket state. */
+    void *instanceData,	/* The socket state. */
     int mask)			/* Events of interest; an OR-ed combination of
 				 * TCL_READABLE, TCL_WRITABLE and
 				 * TCL_EXCEPTION. */
@@ -1663,9 +1655,9 @@ TcpWatchProc(
 
 static int
 TcpGetHandleProc(
-    ClientData instanceData,	/* The socket state. */
+    void *instanceData,	/* The socket state. */
     TCL_UNUSED(int) /*direction*/,
-    ClientData *handlePtr)	/* Where to store the handle. */
+    void **handlePtr)	/* Where to store the handle. */
 {
     TcpState *statePtr = (TcpState *)instanceData;
 
@@ -1732,9 +1724,9 @@ TcpConnect(
 
     for (statePtr->addr = statePtr->addrlist; statePtr->addr != NULL;
 	    statePtr->addr = statePtr->addr->ai_next) {
-        for (statePtr->myaddr = statePtr->myaddrlist;
-                statePtr->myaddr != NULL;
-                statePtr->myaddr = statePtr->myaddr->ai_next) {
+	for (statePtr->myaddr = statePtr->myaddrlist;
+		statePtr->myaddr != NULL;
+		statePtr->myaddr = statePtr->myaddr->ai_next) {
 	    /*
 	     * No need to try combinations of local and remote addresses
 	     * of different families.
@@ -1754,8 +1746,8 @@ TcpConnect(
 	    }
 
 	    /*
-             * Get statePtr lock.
-             */
+	     * Get statePtr lock.
+	     */
 
 	    WaitForSingleObject(tsdPtr->socketListLock, INFINITE);
 
@@ -1767,17 +1759,17 @@ TcpConnect(
 	    Tcl_SetErrno(0);
 
 	    statePtr->sockets->fd = socket(statePtr->myaddr->ai_family,
-                    SOCK_STREAM, 0);
+		    SOCK_STREAM, 0);
 
 	    /*
-             * Free list lock.
-             */
+	     * Free list lock.
+	     */
 
 	    SetEvent(tsdPtr->socketListLock);
 
 	    /*
-             * Continue on socket creation error.
-             */
+	     * Continue on socket creation error.
+	     */
 
 	    if (statePtr->sockets->fd == INVALID_SOCKET) {
 		Tcl_WinConvertError((DWORD) WSAGetLastError());
@@ -1790,14 +1782,14 @@ TcpConnect(
 	     */
 
 	    SetHandleInformation((HANDLE) statePtr->sockets->fd,
-                    HANDLE_FLAG_INHERIT, 0);
+		    HANDLE_FLAG_INHERIT, 0);
 
 	    /*
 	     * Set kernel space buffering
 	     */
 
 	    TclSockMinimumBuffers((void *) statePtr->sockets->fd,
-                    TCP_BUFFER_SIZE);
+		    TCP_BUFFER_SIZE);
 
 	    /*
 	     * Try to bind to a local port.
@@ -1810,7 +1802,7 @@ TcpConnect(
 	    }
 
 	    /*
-	     * For asynchroneous connect set the socket in nonblocking mode
+	     * For asynchronous connect set the socket in nonblocking mode
 	     * and activate connect notification
 	     */
 
@@ -1819,8 +1811,8 @@ TcpConnect(
 		int in_socket_list = 0;
 
 		/*
-                 * Get statePtr lock.
-                 */
+		 * Get statePtr lock.
+		 */
 
 		WaitForSingleObject(tsdPtr->socketListLock, INFINITE);
 
@@ -1848,7 +1840,7 @@ TcpConnect(
 
 		/*
 		 * Set connect mask to connect events
-                 *
+		 *
 		 * This is activated by a SOCKET_SELECT message to the
 		 * notifier thread.
 		 */
@@ -1861,9 +1853,9 @@ TcpConnect(
 
 		SetEvent(tsdPtr->socketListLock);
 
-    		/*
-                 * Activate accept notification.
-                 */
+		/*
+		 * Activate accept notification.
+		 */
 
 		SendSelectMessage(tsdPtr, SELECT, statePtr);
 	    }
@@ -1899,33 +1891,33 @@ TcpConnect(
 		CLEAR_BITS(statePtr->flags, TCP_ASYNC_PENDING);
 
 		/*
-                 * Get statePtr lock.
-                 */
+		 * Get statePtr lock.
+		 */
 
 		WaitForSingleObject(tsdPtr->socketListLock, INFINITE);
 
 		/*
-                 * Get signaled connect error.
-                 */
+		 * Get signaled connect error.
+		 */
 
 		Tcl_WinConvertError((DWORD) statePtr->notifierConnectError);
 
 		/*
-                 * Clear eventual connect flag.
-                 */
+		 * Clear eventual connect flag.
+		 */
 
 		CLEAR_BITS(statePtr->selectEvents, FD_CONNECT);
 
 		/*
-                 * Free list lock.
-                 */
+		 * Free list lock.
+		 */
 
 		SetEvent(tsdPtr->socketListLock);
 	    }
 
 	    /*
 	     * Clear the tsd socket list pointer if we did not wait for
-	     * the FD_CONNECT asynchroneously
+	     * the FD_CONNECT asynchronously
 	     */
 
 	    tsdPtr->pendingTcpState = NULL;
@@ -1977,32 +1969,32 @@ TcpConnect(
 	    statePtr->selectEvents = FD_WRITE|FD_READ;
 
 	    /*
-             * Get statePtr lock.
-             */
+	     * Get statePtr lock.
+	     */
 
 	    WaitForSingleObject(tsdPtr->socketListLock, INFINITE);
 
 	    /*
-             * Signal ready readable and writable events.
-             */
+	     * Signal ready readable and writable events.
+	     */
 
 	    SET_BITS(statePtr->readyEvents, FD_WRITE | FD_READ);
 
 	    /*
-             * Flag error to event routine.
-             */
+	     * Flag error to event routine.
+	     */
 
 	    SET_BITS(statePtr->flags, TCP_ASYNC_FAILED);
 
 	    /*
-             * Save connect error to be reported by 'fconfigure -error'.
-             */
+	     * Save connect error to be reported by 'fconfigure -error'.
+	     */
 
 	    statePtr->connectError = Tcl_GetErrno();
 
 	    /*
-             * Free list lock.
-             */
+	     * Free list lock.
+	     */
 
 	    SetEvent(tsdPtr->socketListLock);
 	}
@@ -2133,7 +2125,7 @@ Tcl_OpenTcpClient(
 
 Tcl_Channel
 Tcl_MakeTcpClientChannel(
-    ClientData sock)		/* The socket to wrap up into a channel. */
+    void *sock)		/* The socket to wrap up into a channel. */
 {
     TcpState *statePtr;
     char channelName[SOCK_CHAN_LENGTH];
@@ -2193,7 +2185,7 @@ Tcl_OpenTcpServerEx(
     Tcl_TcpAcceptProc *acceptProc,
 				/* Callback for accepting connections from new
 				 * clients. */
-    ClientData acceptProcData)	/* Data for the callback. */
+    void *acceptProcData)	/* Data for the callback. */
 {
     SOCKET sock = INVALID_SOCKET;
     unsigned short chosenport = 0;
@@ -2229,7 +2221,7 @@ Tcl_OpenTcpServerEx(
     }
 
     if (!TclCreateSocketAddress(interp, &addrlist, myHost, port, 1,
-            &errorMsg)) {
+	    &errorMsg)) {
 	goto error;
     }
 
@@ -2287,7 +2279,7 @@ Tcl_OpenTcpServerEx(
 	 */
 
 	if (bind(sock, addrPtr->ai_addr,
-                addrPtr->ai_addrlen) == SOCKET_ERROR) {
+		addrPtr->ai_addrlen) == SOCKET_ERROR) {
 	    Tcl_WinConvertError((DWORD) WSAGetLastError());
 	    closesocket(sock);
 	    continue;
@@ -2489,7 +2481,7 @@ InitSockets(void)
 	windowClass.style = 0;
 	windowClass.cbClsExtra = 0;
 	windowClass.cbWndExtra = 0;
-	windowClass.hInstance = TclWinGetTclInstance();
+	windowClass.hInstance = (HINSTANCE)TclWinGetTclInstance();
 	windowClass.hbrBackground = NULL;
 	windowClass.lpszMenuName = NULL;
 	windowClass.lpszClassName = className;
@@ -2610,7 +2602,7 @@ SocketsEnabled(void)
 
 static void
 SocketExitHandler(
-    TCL_UNUSED(ClientData))
+    TCL_UNUSED(void *))
 {
     Tcl_MutexLock(&socketMutex);
 
@@ -2620,7 +2612,7 @@ SocketExitHandler(
      */
 
     TclpFinalizeSockets();
-    UnregisterClassW(className, TclWinGetTclInstance());
+    UnregisterClassW(className, (HINSTANCE)TclWinGetTclInstance());
     initialized = 0;
     Tcl_MutexUnlock(&socketMutex);
 }
@@ -2644,7 +2636,7 @@ SocketExitHandler(
 
 void
 SocketSetupProc(
-    TCL_UNUSED(ClientData),
+    TCL_UNUSED(void *),
     int flags)			/* Event flags as passed to Tcl_DoOneEvent. */
 {
     TcpState *statePtr;
@@ -2662,7 +2654,7 @@ SocketSetupProc(
     for (statePtr = tsdPtr->socketList; statePtr != NULL;
 	    statePtr = statePtr->nextPtr) {
 	if (GOT_BITS(statePtr->readyEvents,
-                statePtr->watchEvents | FD_CONNECT | FD_ACCEPT)) {
+		statePtr->watchEvents | FD_CONNECT | FD_ACCEPT)) {
 	    Tcl_SetMaxBlockTime(&blockTime);
 	    break;
 	}
@@ -2689,7 +2681,7 @@ SocketSetupProc(
 
 static void
 SocketCheckProc(
-    TCL_UNUSED(ClientData),
+    TCL_UNUSED(void *),
     int flags)			/* Event flags as passed to Tcl_DoOneEvent. */
 {
     TcpState *statePtr;
@@ -2819,19 +2811,19 @@ SocketEventProc(
     if (GOT_BITS(statePtr->readyEvents, FD_ACCEPT)) {
 	for (fds = statePtr->sockets; fds != NULL; fds = fds->next) {
 	    /*
-             * Accept the incoming connection request.
-             */
+	     * Accept the incoming connection request.
+	     */
 
 	    len = sizeof(address);
 	    newSocket = accept(fds->fd, &(addr.sa), &len);
 
 	    /*
-             * On Tcl server sockets with multiple OS fds we loop over the fds
+	     * On Tcl server sockets with multiple OS fds we loop over the fds
 	     * trying an accept() on each, so we expect INVALID_SOCKET.  There
 	     * are also other network stack conditions that can result in
 	     * FD_ACCEPT but a subsequent failure on accept() by the time we
 	     * get around to it.
-             *
+	     *
 	     * Access to sockets (acceptEventCount, readyEvents) in socketList
 	     * is still protected by the lock (prevents reintroduction of
 	     * SF Tcl Bug 3056775.
@@ -2857,7 +2849,7 @@ SocketEventProc(
 	    SetEvent(tsdPtr->socketListLock);
 
 	    /*
-             * Caution: TcpAccept() has the side-effect of evaluating the
+	     * Caution: TcpAccept() has the side-effect of evaluating the
 	     * server accept script (via AcceptCallbackProc() in tclIOCmd.c),
 	     * which can close the server socket and invalidate statePtr and
 	     * fds. If TcpAccept() accepts a socket we must return immediately
@@ -2869,7 +2861,7 @@ SocketEventProc(
 	}
 
 	/*
-         * Loop terminated with no sockets accepted; clear the ready mask so
+	 * Loop terminated with no sockets accepted; clear the ready mask so
 	 * we can detect the next connection request. Note that connection
 	 * requests are level triggered, so if there is a request already
 	 * pending, a new event will be generated.
@@ -2985,15 +2977,15 @@ AddSocketInfoFd(
 
     if (fds == NULL) {
 	/*
-         * Add the first FD.
-         */
+	 * Add the first FD.
+	 */
 
 	statePtr->sockets = (TcpFdList *)ckalloc(sizeof(TcpFdList));
 	fds = statePtr->sockets;
     } else {
 	/*
-         * Find end of list and append FD.
-         */
+	 * Find end of list and append FD.
+	 */
 
 	while (fds->next != NULL) {
 	    fds = fds->next;
@@ -3094,34 +3086,34 @@ WaitForSocketEvent(
 	int event_found;
 
 	/*
-         * Get statePtr lock.
-         */
+	 * Get statePtr lock.
+	 */
 
 	WaitForSingleObject(tsdPtr->socketListLock, INFINITE);
 
 	/*
-         * Check if event occured.
-         */
+	 * Check if event occured.
+	 */
 
 	event_found = GOT_BITS(statePtr->readyEvents, events);
 
 	/*
-         * Free list lock.
-         */
+	 * Free list lock.
+	 */
 
 	SetEvent(tsdPtr->socketListLock);
 
 	/*
-         * Exit loop if event occured.
-         */
+	 * Exit loop if event occured.
+	 */
 
 	if (event_found) {
 	    break;
 	}
 
 	/*
-         * Exit loop if event did not occur but this is a non-blocking channel
-         */
+	 * Exit loop if event did not occur but this is a non-blocking channel
+	 */
 
 	if (statePtr->flags & TCP_NONBLOCKING) {
 	    *errorCodePtr = EWOULDBLOCK;
@@ -3472,7 +3464,7 @@ TclWinGetServByName(
 
 static void
 TcpThreadActionProc(
-    ClientData instanceData,
+    void *instanceData,
     int action)
 {
     ThreadSpecificData *tsdPtr;
diff --git a/win/tclooConfig.sh b/win/tclooConfig.sh
index 4c2068c..a400b5b 100644
--- a/win/tclooConfig.sh
+++ b/win/tclooConfig.sh
@@ -16,4 +16,4 @@ TCLOO_STUB_LIB_SPEC=""
 TCLOO_INCLUDE_SPEC=""
 TCLOO_PRIVATE_INCLUDE_SPEC=""
 TCLOO_CFLAGS=""
-TCLOO_VERSION=1.2.0
+TCLOO_VERSION=1.3