From 9f6f5c519abd3e4640e5fed701205a348b0bf006 Mon Sep 17 00:00:00 2001
From: jpeek <jpeek>
Date: Thu, 24 Jun 1999 21:15:13 +0000
Subject: Moved description of regular expression syntax from regexp.n into a
 new re_syntax.n page.  Modified other pages' references to regexp(n). Added a
 few new "see also" entries pointing to re_syntax(n).

---
 doc/CrtInterp.3 |   4 +-
 doc/RegExp.3    |   5 +-
 doc/library.n   |   5 +-
 doc/lsearch.n   |   5 +-
 doc/re_syntax.n | 926 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 doc/regexp.n    | 906 +-----------------------------------------------------
 doc/regsub.n    |   4 +-
 doc/switch.n    |   4 +-
 8 files changed, 948 insertions(+), 911 deletions(-)
 create mode 100644 doc/re_syntax.n

diff --git a/doc/CrtInterp.3 b/doc/CrtInterp.3
index 62055d9..360ff77 100644
--- a/doc/CrtInterp.3
+++ b/doc/CrtInterp.3
@@ -5,7 +5,7 @@
 '\" See the file "license.terms" for information on usage and redistribution
 '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 '\" 
-'\" RCS: @(#) $Id: CrtInterp.3,v 1.2 1998/09/14 18:39:47 stanton Exp $
+'\" RCS: @(#) $Id: CrtInterp.3,v 1.3 1999/06/24 21:15:13 jpeek Exp $
 '\" 
 .so man.macros
 .TH Tcl_CreateInterp 3 7.5 Tcl "Tcl Library Procedures"
@@ -36,7 +36,7 @@ a token for it.  The token is required in calls to most other Tcl
 procedures, such as \fBTcl_CreateCommand\fR, \fBTcl_Eval\fR, and
 \fBTcl_DeleteInterp\fR.
 Clients are only allowed to access a few of the fields of
-Tcl_Interp structures;  see the Tcl_Interp
+Tcl_Interp structures;  see the \fBTcl_Interp\fR
 and \fBTcl_CreateCommand\fR man pages for details.
 The new interpreter is initialized with no defined variables and only
 the built-in Tcl commands.  To bind in additional commands, call
diff --git a/doc/RegExp.3 b/doc/RegExp.3
index 9fefdaf..c8e8887 100644
--- a/doc/RegExp.3
+++ b/doc/RegExp.3
@@ -6,7 +6,7 @@
 '\" See the file "license.terms" for information on usage and redistribution
 '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 '\" 
-'\" RCS: @(#) $Id: RegExp.3,v 1.4 1999/06/17 19:32:21 stanton Exp $
+'\" RCS: @(#) $Id: RegExp.3,v 1.5 1999/06/24 21:15:13 jpeek Exp $
 '\" 
 .so man.macros
 .TH Tcl_RegExpMatch 3 8.1 Tcl "Tcl Library Procedures"
@@ -340,6 +340,7 @@ found, this will be the same as the beginning of the current match.
 If no match was found, then it indicates the earliest point at which a
 match might occur if additional text is appended to the string.
 .VE 8.1
-
+.SH "SEE ALSO"
+re_syntax(n)
 .SH KEYWORDS
 match, pattern, regular expression, string, subexpression, Tcl_RegExpIndices, Tcl_RegExpInfo
diff --git a/doc/library.n b/doc/library.n
index eb20351..44093bb 100644
--- a/doc/library.n
+++ b/doc/library.n
@@ -5,7 +5,7 @@
 '\" See the file "license.terms" for information on usage and redistribution
 '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 '\" 
-'\" RCS: @(#) $Id: library.n,v 1.6 1999/04/16 00:46:35 stanton Exp $
+'\" RCS: @(#) $Id: library.n,v 1.7 1999/06/24 21:15:13 jpeek Exp $
 .so man.macros
 .TH library n "8.0" Tcl "Tcl Built-In Commands"
 .BS
@@ -284,5 +284,8 @@ It is used to detect errors where \fBunknown\fR recurses on itself
 infinitely.
 The variable is unset before \fBunknown\fR returns.
 
+.SH "SEE ALSO"
+re_syntax(n)
+
 .SH KEYWORDS
 auto-exec, auto-load, library, unknown, word, whitespace 
diff --git a/doc/lsearch.n b/doc/lsearch.n
index bcede70..39eddac 100644
--- a/doc/lsearch.n
+++ b/doc/lsearch.n
@@ -5,7 +5,7 @@
 '\" See the file "license.terms" for information on usage and redistribution
 '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 '\" 
-'\" RCS: @(#) $Id: lsearch.n,v 1.2 1998/09/14 18:39:53 stanton Exp $
+'\" RCS: @(#) $Id: lsearch.n,v 1.3 1999/06/24 21:15:13 jpeek Exp $
 '\" 
 .so man.macros
 .TH lsearch n 7.0 Tcl "Tcl Built-In Commands"
@@ -37,7 +37,8 @@ element using the same rules as the \fBstring match\fR command.
 .TP
 \fB\-regexp\fR
 \fIPattern\fR is treated as a regular expression and matched against
-each list element using the same rules as the \fBregexp\fR command.
+each list element using the rules described in the \fBre_syntax\fR
+reference page.
 .PP
 If \fImode\fR is omitted then it defaults to \fB\-glob\fR.
 
diff --git a/doc/re_syntax.n b/doc/re_syntax.n
new file mode 100644
index 0000000..63eb76c
--- /dev/null
+++ b/doc/re_syntax.n
@@ -0,0 +1,926 @@
+'\"
+'\" Copyright (c) 1998 Sun Microsystems, Inc.
+'\" Copyright (c) 1999 Scriptics Corporation
+'\"
+'\" See the file "license.terms" for information on usage and redistribution
+'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+'\" 
+'\" RCS: @(#) $Id: re_syntax.n,v 1.1 1999/06/24 21:15:13 jpeek Exp $
+'\"
+.so man.macros
+.TH re_syntax n "8.1" Tcl "Tcl Built-In Commands"
+.BS
+.SH NAME
+re_syntax \- Syntax of Tcl regular expressions.
+.BE
+
+.SH DESCRIPTION
+.PP
+A \fIregular expression\fR describes strings of characters.
+It's a pattern that matches certain strings and doesn't match others.
+
+.SH "DIFFERENT FLAVORS OF REs"
+.VS 8.1
+Regular expressions (``RE''s), as defined by POSIX, come in two
+flavors: \fIextended\fR REs (``EREs'') and \fIbasic\fR REs (``BREs'').
+EREs are roughly those of the traditional \fIegrep\fR, while BREs are
+roughly those of the traditional \fIed\fR.  This implementation adds
+a third flavor, \fIadvanced\fR REs (``AREs''), basically EREs with
+some significant extensions.
+.PP
+This manual page primarily describes AREs.  BREs mostly exist for
+backward compatibility in some old programs; they will be discussed at
+the end.  POSIX EREs are almost an exact subset of AREs.  Features of
+AREs that are not present in EREs will be indicated.
+
+.SH "REGULAR EXPRESSION SYNTAX"
+.PP
+Tcl regular expressions are implemented using the package written by
+Henry Spencer, based on the 1003.2 spec and some (not quite all) of
+the Perl5 extensions (thanks, Henry!).  Much of the description of
+regular expressions below is copied verbatim from his manual entry.
+.PP
+An ARE is one or more \fIbranches\fR,
+separated by `\fB|\fR',
+matching anything that matches any of the branches.
+.PP
+A branch is zero or more \fIconstraints\fR or \fIquantified atoms\fR,
+concatenated.
+It matches a match for the first, followed by a match for the second, etc;
+an empty branch matches the empty string.
+.PP
+A quantified atom is an \fIatom\fR possibly followed
+by a single \fIquantifier\fR.
+Without a quantifier, it matches a match for the atom.
+The quantifiers,
+and what a so-quantified atom matches, are:
+.RS 2
+.TP 6
+\fB*\fR
+a sequence of 0 or more matches of the atom
+.TP
+\fB+\fR
+a sequence of 1 or more matches of the atom
+.TP
+\fB?\fR
+a sequence of 0 or 1 matches of the atom
+.TP
+\fB{\fIm\fB}\fR
+a sequence of exactly \fIm\fR matches of the atom
+.TP
+\fB{\fIm\fB,}\fR
+a sequence of \fIm\fR or more matches of the atom
+.TP
+\fB{\fIm\fB,\fIn\fB}\fR
+a sequence of \fIm\fR through \fIn\fR (inclusive) matches of the atom;
+\fIm\fR may not exceed \fIn\fR
+.TP
+\fB*?  +?  ??  {\fIm\fB}?  {\fIm\fB,}?  {\fIm\fB,\fIn\fB}?\fR
+\fInon-greedy\fR quantifiers,
+which match the same possibilities,
+but prefer the smallest number rather than the largest number
+of matches (see MATCHING)
+.RE
+.PP
+The forms using
+\fB{\fR and \fB}\fR
+are known as \fIbound\fRs.
+The numbers
+\fIm\fR and \fIn\fR are unsigned decimal integers
+with permissible values from 0 to 255 inclusive.
+.PP
+An atom is one of:
+.RS 2
+.TP 6
+\fB(\fIre\fB)\fR
+(where \fIre\fR is any regular expression)
+matches a match for
+\fIre\fR, with the match noted for possible reporting
+.TP
+\fB(?:\fIre\fB)\fR
+as previous,
+but does no reporting
+(a ``non-capturing'' set of parentheses)
+.TP
+\fB()\fR
+matches an empty string,
+noted for possible reporting
+.TP
+\fB(?:)\fR
+matches an empty string,
+without reporting
+.TP
+\fB[\fIchars\fB]\fR
+a \fIbracket expression\fR,
+matching any one of the \fIchars\fR (see BRACKET EXPRESSIONS for more detail)
+.TP
+ \fB.\fR
+matches any single character
+.TP
+\fB\e\fIk\fR
+(where \fIk\fR is a non-alphanumeric character)
+matches that character taken as an ordinary character,
+e.g. \e\e matches a backslash character
+.TP
+\fB\e\fIc\fR
+where \fIc\fR is alphanumeric
+(possibly followed by other characters),
+an \fIescape\fR (AREs only),
+see ESCAPES below
+.TP
+\fB{\fR
+when followed by a character other than a digit,
+matches the left-brace character `\fB{\fR';
+when followed by a digit, it is the beginning of a
+\fIbound\fR (see above)
+.TP
+\fIx\fR
+where \fIx\fR is
+a single character with no other significance, matches that character.
+.RE
+.PP
+A \fIconstraint\fR matches an empty string when specific conditions
+are met.
+A constraint may not be followed by a quantifier.
+The simple constraints are as follows; some more constraints are
+described later, under ESCAPES.
+.RS 2
+.TP 8
+\fB^\fR
+matches at the beginning of a line
+.TP
+\fB$\fR
+matches at the end of a line
+.TP
+\fB(?=\fIre\fB)\fR
+\fIpositive lookahead\fR (AREs only), matches at any point
+where a substring matching \fIre\fR begins
+.TP
+\fB(?!\fIre\fB)\fR
+\fInegative lookahead\fR (AREs only), matches at any point
+where no substring matching \fIre\fR begins
+.RE
+.PP
+The lookahead constraints may not contain back references (see later),
+and all parentheses within them are considered non-capturing.
+.PP
+An RE may not end with `\fB\e\fR'.
+
+.SH "BRACKET EXPRESSIONS"
+A \fIbracket expression\fR is a list of characters enclosed in `\fB[\|]\fR'.
+It normally matches any single character from the list (but see below).
+If the list begins with `\fB^\fR',
+it matches any single character
+(but see below) \fInot\fR from the rest of the list.
+.PP
+If two characters in the list are separated by `\fB\-\fR',
+this is shorthand
+for the full \fIrange\fR of characters between those two (inclusive) in the
+collating sequence,
+e.g.
+\fB[0\-9]\fR
+in ASCII matches any decimal digit.
+Two ranges may not share an
+endpoint, so e.g.
+\fBa\-c\-e\fR
+is illegal.
+Ranges are very collating-sequence-dependent,
+and portable programs should avoid relying on them.
+.PP
+To include a literal
+\fB]\fR
+or
+\fB\-\fR
+in the list,
+the simplest method is to
+enclose it in
+\fB[.\fR and \fB.]\fR
+to make it a collating element (see below).
+Alternatively,
+make it the first character
+(following a possible `\fB^\fR'),
+or (AREs only) precede it with `\fB\e\fR'.
+Alternatively, for `\fB\-\fR',
+make it the last character,
+or the second endpoint of a range.
+To use a literal
+\fB\-\fR
+as the first endpoint of a range,
+make it a collating element
+or (AREs only) precede it with `\fB\e\fR'.
+With the exception of these, some combinations using
+\fB[\fR
+(see next
+paragraphs), and escapes,
+all other special characters lose their
+special significance within a bracket expression.
+.PP
+Within a bracket expression, a collating element (a character,
+a multi-character sequence that collates as if it were a single character,
+or a collating-sequence name for either)
+enclosed in
+\fB[.\fR and \fB.]\fR
+stands for the
+sequence of characters of that collating element.
+The sequence is a single element of the bracket expression's list.
+A bracket expression in a locale which has
+multi-character collating elements
+can thus match more than one character.
+Most insidiously, if
+\fB^\fR
+is used,
+this can happen even if no multi-character collating 
+elements appear in the bracket expression!
+If the collating sequence includes a
+\fBch\fR
+multi-character collating element,
+then the RE
+\fB[[.ch.]]*c\fR
+matches the first five characters
+of `\fBchchcc\fR',
+and the RE
+\fB[^c]b\fR
+matches all of `\fBchb\fR'.
+.PP
+Within a bracket expression, a collating element enclosed in
+\fB[=\fR
+and
+\fB=]\fR
+is an equivalence class, standing for the sequences of characters
+of all collating elements equivalent to that one, including itself.
+(If there are no other equivalent collating elements,
+the treatment is as if the enclosing delimiters were `\fB[.\fR'\&
+and `\fB.]\fR'.)
+For example, if
+\fBo\fR
+and
+\fB\o'o^'\fR
+are the members of an equivalence class,
+then `\fB[[=o=]]\fR', `\fB[[=\o'o^'=]]\fR',
+and `\fB[o\o'o^']\fR'\&
+are all synonymous.
+An equivalence class may not be an endpoint
+of a range.
+.PP
+Within a bracket expression, the name of a \fIcharacter class\fR enclosed
+in
+\fB[:\fR
+and
+\fB:]\fR
+stands for the list of all characters
+(not all collating elements!)
+belonging to that
+class.
+Standard character classes are (*** CHECK THESE! ***):
+.PP
+.RS
+.ne 5
+.nf
+.ta 3c
+\fBalpha\fR	A letter. 
+\fBupper\fR	An upper-case letter. 
+\fBlower\fR	A lower-case letter. 
+\fBdigit\fR	A decimal digit. 
+\fBxdigit\fR	A hexadecimal digit. 
+\fBalnum\fR	An alphanumeric (letter or digit). 
+\fBspace\fR	A character producing white space in displayed text. 
+\fBpunct\fR	A punctuation character. 
+\fBprint\fR	A printing character. 
+\fBgraph\fR	A character with a visible representation. 
+\fBcntrl\fR	A control character. 
+.fi
+.RE
+.PP
+A locale may provide others. (*** NOT ANYMORE, TRUE? ***)
+A character class may not be used as an endpoint of a range.
+.PP
+There are two special cases of bracket expressions:
+the bracket expressions
+\fB[[:<:]]\fR
+and
+\fB[[:>:]]\fR
+are constraints, matching empty strings at
+the beginning and end of a word respectively.
+'\" note, discussion of escapes below references this definition of word
+A word is defined as a sequence of
+word characters
+which is neither preceded nor followed by
+word characters.
+A word character is an
+\fIalnum\fR
+character (as defined by
+\fIctype\fR(3))
+or an underscore
+(\fB_\fR).
+These special bracket expressions are deprecated;
+users of AREs should use constraint escapes instead (see below).
+.SH ESCAPES
+Escapes (AREs only), which begin with a
+\fB\e\fR
+followed by an alphanumeric character,
+come in several varieties:
+character entry, class shorthands, constraint escapes, and back references.
+A
+\fB\e\fR
+followed by an alphanumeric character but not constituting
+a valid escape is illegal in AREs.
+In EREs, there are no escapes:
+outside a bracket expression,
+a
+\fB\e\fR
+followed by an alphanumeric character merely stands for that
+character as an ordinary character,
+and inside a bracket expression,
+\fB\e\fR
+is an ordinary character.
+(The latter is the one actual incompatibility between EREs and AREs.)
+.PP
+Character-entry escapes (AREs only) exist to make it easier to specify
+non-printing and otherwise inconvenient characters in REs:
+.RS 2
+.TP 5
+\fB\ea\fR
+alert, aka bell, character, as in C
+.TP
+\fB\eb\fR
+backspace, as in C
+.TP
+\fB\eB\fR
+synonym for
+\fB\e\fR
+to help reduce backslash doubling in some
+applications where there are multiple levels of backslash processing
+.TP
+\fB\ec\fIX\fR
+(where X is any character) the character whose
+low-order 5 bits are the same as those of
+\fIX\fR,
+and whose other bits are all zero
+.TP
+\fB\ee\fR
+the character whose collating-sequence name
+is `\fBESC\fR',
+or failing that, the character with octal value 033
+.TP
+\fB\ef\fR
+formfeed, as in C
+.TP
+\fB\en\fR
+newline, as in C
+.TP
+\fB\er\fR
+carriage return, as in C
+.TP
+\fB\et\fR
+horizontal tab, as in C
+.TP
+\fB\eu\fIwxyz\fR
+(where
+\fIwxyz\fR
+is exactly four hexadecimal digits)
+the Unicode character
+\fBU+\fIwxyz\fR
+in the local byte ordering
+.TP
+\fB\eU\fIstuvwxyz\fR
+(where
+\fIstuvwxyz\fR
+is exactly eight hexadecimal digits)
+reserved for a somewhat-hypothetical Unicode extension to 32 bits
+.TP
+\fB\ev\fR
+vertical tab, as in C
+are all available.
+.TP
+\fB\ex\fIhhh\fR
+(where
+\fIhhh\fR
+is any sequence of hexadecimal digits)
+the character whose hexadecimal value is
+\fB0x\fIhhh\fR
+(a single character no matter how many hexadecimal digits are used).
+.TP
+\fB\e0\fR
+the character whose value is
+\fB0\fR
+.TP
+\fB\e\fIxy\fR
+(where
+\fIxy\fR
+is exactly two octal digits,
+and is not a
+\fIback reference\fR (see below))
+the character whose octal value is
+\fB0\fIxy\fR
+.TP
+\fB\e\fIxyz\fR
+(where
+\fIxyz\fR
+is exactly three octal digits,
+and is not a
+back reference (see below))
+the character whose octal value is
+\fB0\fIxyz\fR
+.RE
+.PP
+Hexadecimal digits are `\fB0\fR'-`\fB9\fR', `\fBa\fR'-`\fBf\fR',
+and `\fBA\fR'-`\fBF\fR'.
+Octal digits are `\fB0\fR'-`\fB7\fR'.
+.PP
+The character-entry escapes are always taken as ordinary characters.
+For example,
+\fB\e135\fR
+is
+\fB]\fR
+in ASCII,
+but
+\fB\e135\fR
+does not terminate a bracket expression.
+Beware, however, that some applications (e.g., C compilers) interpret 
+such sequences themselves before the regular-expression package
+gets to see them, which may require doubling (quadrupling, etc.) the `\fB\e\fR'.
+.PP
+Class-shorthand escapes (AREs only) provide shorthands for certain commonly-used
+character classes:
+.RS 2
+.TP 10
+\fB\ed\fR
+\fB[[:digit:]]\fR
+.TP
+\fB\es\fR
+\fB[[:space:]]\fR
+.TP
+\fB\ew\fR
+\fB[[:alnum:]_]\fR
+(note underscore)
+.TP
+\fB\eD\fR
+\fB[^[:digit:]]\fR
+.TP
+\fB\eS\fR
+\fB[^[:space:]]\fR
+.TP
+\fB\eW\fR
+\fB[^[:alnum:]_]\fR
+(note underscore)
+.RE
+.PP
+Within bracket expressions, `\fB\ed\fR', `\fB\es\fR',
+and `\fB\ew\fR'\&
+lose their outer brackets,
+and `\fB\eD\fR', `\fB\eS\fR',
+and `\fB\eW\fR'\&
+are illegal.
+.PP
+A constraint escape (AREs only) is a constraint,
+matching the empty string if specific conditions are met,
+written as an escape:
+.RS 2
+.TP 6
+\fB\eA\fR
+matches only at the beginning of the string
+(see MATCHING, below, for how this differs from `\fB^\fR')
+.TP
+\fB\em\fR
+matches only at the beginning of a word
+.TP
+\fB\eM\fR
+matches only at the end of a word
+.TP
+\fB\ey\fR
+matches only at the beginning or end of a word
+.TP
+\fB\eY\fR
+matches only at a point which is not the beginning or end of a word
+.TP
+\fB\eZ\fR
+matches only at the end of the string
+(see MATCHING, below, for how this differs from `\fB$\fR')
+.TP
+\fB\e\fIm\fR
+(where
+\fIm\fR
+is a nonzero digit) a \fIback reference\fR, see below
+.TP
+\fB\e\fImnn\fR
+(where
+\fIm\fR
+is a nonzero digit, and
+\fInn\fR
+is some more digits,
+and the decimal value
+\fImnn\fR
+is not greater than the number of closing capturing parentheses seen so far)
+a \fIback reference\fR, see below
+.RE
+.PP
+A word is defined as in the specification of
+\fB[[:<:]]\fR
+and
+\fB[[:>:]]\fR
+above.
+Constraint escapes are illegal within bracket expressions.
+.PP
+A back reference (AREs only) matches the same string matched by the parenthesized
+subexpression specified by the number,
+so that (e.g.)
+\fB([bc])\e1\fR
+matches
+\fBbb\fR
+or
+\fBcc\fR
+but not `\fBbc\fR'.
+The subexpression must entirely precede the back reference in the RE.
+Subexpressions are numbered in the order of their leading parentheses.
+Non-capturing parentheses do not define subexpressions.
+.PP
+There is an inherent historical ambiguity between octal character-entry 
+escapes and back references, which is resolved by heuristics,
+as hinted at above.
+A leading zero always indicates an octal escape.
+A single non-zero digit, not followed by another digit,
+is always taken as a back reference.
+A multi-digit sequence not starting with a zero is taken as a back 
+reference if it comes after a suitable subexpression
+(i.e. the number is in the legal range for a back reference),
+and otherwise is taken as octal.
+.SH "METASYNTAX"
+In addition to the main syntax described above, there are some special
+forms and miscellaneous syntactic facilities available.
+.PP
+Normally the flavor of RE being used is specified by
+application-dependent means.
+However, this can be overridden by a \fIdirector\fR.
+If an RE of any flavor begins with `\fB***:\fR',
+the rest of the RE is an ARE.
+If an RE of any flavor begins with `\fB***=\fR',
+the rest of the RE is taken to be a literal string,
+with all characters considered ordinary characters.
+.PP
+An ARE may begin with \fIembedded options\fR:
+a sequence
+\fB(?\fIxyz\fB)\fR
+(where
+\fIxyz\fR
+is one or more alphabetic characters)
+specifies options affecting the rest of the RE.
+These supplement, and can override,
+any options specified by the application.
+The available option letters are:
+.RS 2
+.TP 3
+\fBb\fR
+rest of RE is a BRE
+.TP 3
+\fBc\fR
+case-sensitive matching (usual default)
+.TP 3
+\fBe\fR
+rest of RE is an ERE
+.TP 3
+\fBi\fR
+case-insensitive matching (see MATCHING, below)
+.TP 3
+\fBm\fR
+historical synonym for
+\fBn\fR
+.TP 3
+\fBn\fR
+newline-sensitive matching (see MATCHING, below)
+.TP 3
+\fBp\fR
+partial newline-sensitive matching (see MATCHING, below)
+.TP 3
+\fBq\fR
+rest of RE is a literal (``quoted'') string, all ordinary characters
+.TP 3
+\fBs\fR
+non-newline-sensitive matching (usual default)
+.TP 3
+\fBt\fR
+tight syntax (usual default; see below)
+.TP 3
+\fBw\fR
+inverse partial newline-sensitive (``weird'') matching (see MATCHING, below)
+.TP 3
+\fBx\fR
+expanded syntax (see below)
+.RE
+.PP
+Embedded options take effect at the
+\fB)\fR
+terminating the sequence.
+They are available only at the start of an ARE,
+and may not be used later within it.
+.PP
+In addition to the usual (\fItight\fR) RE syntax, in which all characters are
+significant, there is an \fIexpanded\fR syntax,
+available in all flavors of RE
+with the \fB-expanded\fR switch, or in AREs with the embedded x option.
+In the expanded syntax,
+white-space characters are ignored
+and all characters between a
+\fB#\fR
+and the following newline (or the end of the RE) are ignored,
+permitting paragraphing and commenting a complex RE.
+There are three exceptions to that basic rule:
+.RS 2
+.PP
+a white-space character or `\fB#\fR' preceded by `\fB\e\fR' is retained
+.PP
+white space or `\fB#\fR' within a bracket expression is retained
+.PP
+white space and comments are illegal within multi-character symbols
+like the ARE `\fB(?:\fR' or the BRE `\fB\e(\fR'
+.RE
+.PP
+Expanded-syntax
+white-space characters are blank, tab, newline, etc. (any character
+defined as \fIspace\fR by
+\fIctype\fR(3)).
+Exactly how a multi-line expanded-syntax RE
+can be entered interactively by a user,
+if at all, is application-specific;
+expanded syntax is primarily a scripting facility.
+.PP
+Finally, in an ARE,
+outside bracket expressions, the sequence `\fB(?#\fIttt\fB)\fR'
+(where
+\fIttt\fR
+is any text not containing a `\fB)\fR')
+is a comment,
+completely ignored.
+Again, this is not allowed between the characters of
+multi-character symbols like `\fB(?:\fR'.
+Such comments are more a historical artifact than a useful facility,
+and their use is deprecated;
+use the expanded syntax instead.
+.PP
+\fINone\fR of these metasyntax extensions is available if the application
+(or an initial
+\fB***=\fR
+director)
+has specified that the user's input be treated as a literal string
+rather than as an RE.
+.SH MATCHING
+In the event that an RE could match more than one substring of a given
+string,
+the RE matches the one starting earliest in the string.
+If the RE could match more than one substring starting at that point,
+its choice is determined by its \fIpreference\fR:
+either the longest substring, or the shortest.
+.PP
+Most atoms, and all constraints, have no preference.
+A parenthesized RE has the same preference (possibly none) as the RE.
+A quantified atom with quantifier
+\fB{\fIm\fB}\fR
+or
+\fB{\fIm\fB}?\fR
+has the same preference (possibly none) as the atom itself.
+A quantified atom with other normal quantifiers (including
+\fB{\fIm\fB,\fIn\fB}\fR
+with
+\fIm\fR
+equal to
+\fIn\fR)
+prefers longest match.
+A quantified atom with other non-greedy quantifiers (including
+\fB{\fIm\fB,\fIn\fB}?\fR
+with
+\fIm\fR
+equal to
+\fIn\fR)
+prefers shortest match.
+A branch has the same preference as the first quantified atom in it
+which has a preference.
+An RE consisting of two or more branches connected by the
+\fB|\fR
+operator prefers longest match.
+.PP
+Subject to the constraints imposed by the rules for matching the whole RE,
+subexpressions also match the longest or shortest possible substrings,
+based on their preferences,
+with subexpressions starting earlier in the RE taking priority over
+ones starting later.
+Note that outer subexpressions thus take priority over
+their component subexpressions.
+.PP
+Note that the quantifiers
+\fB{1,1}\fR
+and
+\fB{1,1}?\fR
+can be used to force longest and shortest preference, respectively,
+on a subexpression or a whole RE.
+.PP
+Match lengths are measured in characters, not collating elements.
+An empty string is considered longer than no match at all.
+For example,
+\fBbb*\fR
+matches the three middle characters of `\fBabbbc\fR',
+\fB(week|wee)(night|knights)\fR
+matches all ten characters of `\fBweeknights\fR',
+when
+\fB(.*).*\fR
+is matched against
+\fBabc\fR
+the parenthesized subexpression
+matches all three characters, and
+when
+\fB(a*)*\fR
+is matched against
+\fBbc\fR
+both the whole RE and the parenthesized
+subexpression match an empty string.
+.PP
+If case-independent matching is specified,
+the effect is much as if all case distinctions had vanished from the
+alphabet.
+When an alphabetic that exists in multiple cases appears as an
+ordinary character outside a bracket expression, it is effectively
+transformed into a bracket expression containing both cases,
+so that
+\fBx\fR
+becomes `\fB[xX]\fR'.
+When it appears inside a bracket expression, all case counterparts
+of it are added to the bracket expression, so that
+\fB[x]\fR
+becomes
+\fB[xX]\fR
+and
+\fB[^x]\fR
+becomes `\fB[^xX]\fR'.
+.PP
+If newline-sensitive matching is specified, \fB.\fR
+and bracket expressions using
+\fB^\fR
+will never match the newline character
+(so that matches will never cross newlines unless the RE
+explicitly arranges it)
+and
+\fB^\fR
+and
+\fB$\fR
+will match the empty string after and before a newline
+respectively, in addition to matching at beginning and end of string
+respectively.
+ARE
+\fB\eA\fR
+and
+\fB\eZ\fR
+continue to match beginning or end of string \fIonly\fR.
+.PP
+If partial newline-sensitive matching is specified,
+this affects \fB.\fR
+and bracket expressions
+as with newline-sensitive matching, but not
+\fB^\fR
+and `\fB$\fR'.
+.PP
+If inverse partial newline-sensitive matching is specified,
+this affects
+\fB^\fR
+and
+\fB$\fR
+as with
+newline-sensitive matching,
+but not \fB.\fR
+and bracket expressions.
+This isn't very useful but is provided for symmetry.
+.SH "LIMITS AND COMPATIBILITY"
+No particular limit is imposed on the length of REs.
+Programs intended to be highly portable should not employ REs longer
+than 256 bytes,
+as a POSIX-compliant implementation can refuse to accept such REs.
+.PP
+The only feature of AREs that is actually incompatible with
+POSIX EREs is that
+\fB\e\fR
+does not lose its special
+significance inside bracket expressions.
+All other ARE features use syntax which is illegal or has
+undefined or unspecified effects in POSIX EREs;
+the
+\fB***\fR
+syntax of directors likewise is outside the POSIX
+syntax for both BREs and EREs.
+.PP
+Many of the ARE extensions are borrowed from Perl, but some have
+been changed to clean them up, and a few Perl extensions are not present.
+Incompatibilities of note include `\fB\eb\fR', `\fB\eB\fR',
+the lack of special treatment for a trailing newline,
+the addition of complemented bracket expressions to the things
+affected by newline-sensitive matching,
+the restrictions on parentheses and back references in lookahead constraints,
+and the longest/shortest-match (rather than first-match) matching semantics.
+.PP
+The matching rules for REs containing both normal and non-greedy quantifiers
+have changed since early beta-test versions of this package.
+(The new rules are much simpler and cleaner,
+but don't work as hard at guessing the user's real intentions.)
+.PP
+Henry Spencer's original 1986 \fIregexp\fR package,
+still in widespread use (e.g., in pre-8.1 releases of Tcl),
+implemented an early version of today's EREs.
+There are four incompatibilities between \fIregexp\fR's near-EREs
+(`RREs' for short) and AREs.
+In roughly increasing order of significance:
+.PP
+.RS
+In AREs,
+\fB\e\fR
+followed by an alphanumeric character is either an
+escape or an error,
+while in RREs, it was just another way of writing the 
+alphanumeric.
+This should not be a problem because there was no reason to write
+such a sequence in RREs.
+.PP
+\fB{\fR
+followed by a digit in an ARE is the beginning of a bound,
+while in RREs,
+\fB{\fR
+was always an ordinary character.
+Such sequences should be rare,
+and will often result in an error because following characters
+will not look like a valid bound.
+.PP
+In AREs,
+\fB\e\fR
+remains a special character within `\fB[\|]\fR',
+so a literal
+\fB\e\fR
+within
+\fB[\|]\fR
+must be written `\fB\e\e\fR'.
+\fB\e\e\fR
+also gives a literal
+\fB\e\fR
+within
+\fB[\|]\fR
+in RREs,
+but only truly paranoid programmers routinely doubled the backslash.
+.PP
+AREs report the longest/shortest match for the RE,
+rather than the first found in a specified search order.
+This may affect some RREs which were written in the expectation that
+the first match would be reported.
+(The careful crafting of RREs to optimize the search order for fast
+matching is obsolete (AREs examine all possible matches
+in parallel, and their performance is largely insensitive to their
+complexity) but cases where the search order was exploited to deliberately 
+find a match which was \fInot\fR the longest/shortest will need rewriting.)
+.RE
+
+.SH "BASIC REGULAR EXPRESSIONS"
+BREs differ from EREs in several respects.  `\fB|\fR', `\fB+\fR',
+and
+\fB?\fR
+are ordinary characters and there is no equivalent
+for their functionality.
+The delimiters for bounds are
+\fB\e{\fR
+and `\fB\e}\fR',
+with
+\fB{\fR
+and
+\fB}\fR
+by themselves ordinary characters.
+The parentheses for nested subexpressions are
+\fB\e(\fR
+and `\fB\e)\fR',
+with
+\fB(\fR
+and
+\fB)\fR
+by themselves ordinary characters.
+\fB^\fR
+is an ordinary character except at the beginning of the
+RE or the beginning of a parenthesized subexpression,
+\fB$\fR
+is an ordinary character except at the end of the
+RE or the end of a parenthesized subexpression,
+and
+\fB*\fR
+is an ordinary character if it appears at the beginning of the
+RE or the beginning of a parenthesized subexpression
+(after a possible leading `\fB^\fR').
+Finally,
+single-digit back references are available,
+and
+\fB\e<\fR
+and
+\fB\e>\fR
+are synonyms for
+\fB[[:<:]]\fR
+and
+\fB[[:>:]]\fR
+respectively;
+no other escapes are available.
+
+.VE 8.1
+
+.SH "SEE ALSO"
+RegExp(3), regexp(n), regsub(n), lsearch(n), switch(n), text(n)
+
+.SH KEYWORDS
+match, regular expression, string
diff --git a/doc/regexp.n b/doc/regexp.n
index 2f6c4b6..03010e3 100644
--- a/doc/regexp.n
+++ b/doc/regexp.n
@@ -4,7 +4,7 @@
 '\" See the file "license.terms" for information on usage and redistribution
 '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 '\" 
-'\" RCS: @(#) $Id: regexp.n,v 1.5 1999/05/06 19:14:42 stanton Exp $
+'\" RCS: @(#) $Id: regexp.n,v 1.6 1999/06/24 21:15:13 jpeek Exp $
 '\" 
 .so man.macros
 .TH regexp n 8.1 Tcl "Tcl Built-In Commands"
@@ -21,6 +21,8 @@ regexp \- Match a regular expression against a string
 .PP
 Determines whether the regular expression \fIexp\fR matches part or
 all of \fIstring\fR and returns 1 if it does, 0 if it doesn't.
+(Regular expression matching is described in the \fBre_syntax\fR
+reference page.)
 .LP
 If additional arguments are specified after \fIstring\fR then they
 are treated as the names of variables in which to return
@@ -93,906 +95,8 @@ portion of the expression that wasn't matched), then the corresponding
 \fIsubMatchVar\fR will be set to ``\fB\-1 \-1\fR'' if \fB\-indices\fR
 has been specified or to an empty string otherwise.
 
-.SH "DIFFERENT FLAVORS OF REs"
-.VS 8.1
-Regular expressions (``RE''s), as defined by POSIX, come in two
-flavors: \fIextended\fR REs (``EREs'') and \fIbasic\fR REs (``BREs'').
-EREs are roughly those of the traditional \fIegrep\fR, while BREs are
-roughly those of the traditional \fIed\fR .  This implementation adds
-a third flavor, \fIadvanced\fR REs (``AREs''), basically EREs with
-some significant extensions.
-.PP
-This manual page primarily describes AREs.  BREs mostly exist for
-backward compatibility in some old programs; they will be discussed at
-the end.  POSIX EREs are almost an exact subset of AREs.  Features of
-AREs that are not present in EREs will be indicated.
-
-.SH "REGULAR EXPRESSION SYNTAX"
-.PP
-Tcl regular expressions are implemented using the package written by
-Henry Spencer, based on the 1003.2 spec and some (not quite all) of
-the Perl5 extensions (thanks, Henry!).  Much of the description of
-regular expressions below is copied verbatim from his manual entry.
-.PP
-An ARE is one or more \fIbranches\fR,
-separated by `\fB|\fR',
-matching anything that matches any of the branches.
-.PP
-A branch is zero or more \fIconstraints\fR or \fIquantified atoms\fR,
-concatenated.
-It matches a match for the first, followed by a match for the second, etc;
-an empty branch matches the empty string.
-.PP
-A quantified atom is an \fIatom\fR possibly followed
-by a single \fIquantifier\fR.
-Without a quantifier, it matches a match for the atom.
-The quantifiers,
-and what a so-quantified atom matches, are:
-.RS 2
-.TP 6
-\fB*\fR
-a sequence of 0 or more matches of the atom
-.TP
-\fB+\fR
-a sequence of 1 or more matches of the atom
-.TP
-\fB?\fR
-a sequence of 0 or 1 matches of the atom
-.TP
-\fB{\fIm\fB}\fR
-a sequence of exactly \fIm\fR matches of the atom
-.TP
-\fB{\fIm\fB,}\fR
-a sequence of \fIm\fR or more matches of the atom
-.TP
-\fB{\fIm\fB,\fIn\fB}\fR
-a sequence of \fIm\fR through \fIn\fR (inclusive) matches of the atom;
-\fIm\fR may not exceed \fIn\fR
-.TP
-\fB*?  +?  ??  {\fIm\fB}?  {\fIm\fB,}?  {\fIm\fB,\fIn\fB}?\fR
-\fInon-greedy\fR quantifiers,
-which match the same possibilities,
-but prefer the smallest number rather than the largest number
-of matches (see MATCHING)
-.RE
-.PP
-The forms using
-\fB{\fR and \fB}\fR
-are known as \fIbound\fRs.
-The numbers
-\fIm\fR and \fIn\fR are unsigned decimal integers
-with permissible values from 0 to 255 inclusive.
-.PP
-An atom is one of:
-.RS 2
-.TP 6
-\fB(\fIre\fB)\fR
-(where \fIre\fR is any regular expression)
-matches a match for
-\fIre\fR, with the match noted for possible reporting
-.TP
-\fB(?:\fIre\fB)\fR
-as previous,
-but does no reporting
-(a ``non-capturing'' set of parentheses)
-.TP
-\fB()\fR
-matches an empty string,
-noted for possible reporting
-.TP
-\fB(?:)\fR
-matches an empty string,
-without reporting
-.TP
-\fB[\fIchars\fB]\fR
-a \fIbracket expression\fR,
-matching any one of the \fIchars\fR (see BRACKET EXPRESSIONS for more detail)
-.TP
- \fB.\fR
-matches any single character
-.TP
-\fB\e\fIk\fR
-(where \fIk\fR is a non-alphanumeric character)
-matches that character taken as an ordinary character,
-e.g. \e\e matches a backslash character
-.TP
-\fB\e\fIc\fR
-where \fIc\fR is alphanumeric
-(possibly followed by other characters),
-an \fIescape\fR (AREs only),
-see ESCAPES below
-.TP
-\fB{\fR
-when followed by a character other than a digit,
-matches the left-brace character `\fB{\fR';
-when followed by a digit, it is the beginning of a
-\fIbound\fR (see above)
-.TP
-\fIx\fR
-where \fIx\fR is
-a single character with no other significance, matches that character.
-.RE
-.PP
-A \fIconstraint\fR matches an empty string when specific conditions
-are met.
-A constraint may not be followed by a quantifier.
-The simple constraints are as follows; some more constraints are
-described later, under ESCAPES.
-.RS 2
-.TP 8
-\fB^\fR
-matches at the beginning of a line
-.TP
-\fB$\fR
-matches at the end of a line
-.TP
-\fB(?=\fIre\fB)\fR
-\fIpositive lookahead\fR (AREs only), matches at any point
-where a substring matching \fIre\fR begins
-.TP
-\fB(?!\fIre\fB)\fR
-\fInegative lookahead\fR (AREs only), matches at any point
-where no substring matching \fIre\fR begins
-.RE
-.PP
-The lookahead constraints may not contain back references (see later),
-and all parentheses within them are considered non-capturing.
-.PP
-An RE may not end with `\fB\e\fR'.
-
-.SH "BRACKET EXPRESSIONS"
-A \fIbracket expression\fR is a list of characters enclosed in `\fB[\|]\fR'.
-It normally matches any single character from the list (but see below).
-If the list begins with `\fB^\fR',
-it matches any single character
-(but see below) \fInot\fR from the rest of the list.
-.PP
-If two characters in the list are separated by `\fB\-\fR',
-this is shorthand
-for the full \fIrange\fR of characters between those two (inclusive) in the
-collating sequence,
-e.g.
-\fB[0\-9]\fR
-in ASCII matches any decimal digit.
-Two ranges may not share an
-endpoint, so e.g.
-\fBa\-c\-e\fR
-is illegal.
-Ranges are very collating-sequence-dependent,
-and portable programs should avoid relying on them.
-.PP
-To include a literal
-\fB]\fR
-or
-\fB\-\fR
-in the list,
-the simplest method is to
-enclose it in
-\fB[.\fR
-and
-\fB.]\fR
-to make it a collating element (see below).
-Alternatively,
-make it the first character
-(following a possible `\fB^\fR'),
-or (AREs only) precede it with `\fB\e\fR'.
-Alternatively, for `\fB\-\fR',
-make it the last character,
-or the second endpoint of a range.
-To use a literal
-\fB\-\fR
-as the first endpoint of a range,
-make it a collating element
-or (AREs only) precede it with `\fB\e\fR'.
-With the exception of these, some combinations using
-\fB[\fR
-(see next
-paragraphs), and escapes,
-all other special characters lose their
-special significance within a bracket expression.
-.PP
-Within a bracket expression, a collating element (a character,
-a multi-character sequence that collates as if it were a single character,
-or a collating-sequence name for either)
-enclosed in
-\fB[.\fR
-and
-\fB.]\fR
-stands for the
-sequence of characters of that collating element.
-The sequence is a single element of the bracket expression's list.
-A bracket expression in a locale which has
-multi-character collating elements
-can thus match more than one character.
-Most insidiously, if
-\fB^\fR
-is used,
-this can happen even if no multi-character collating 
-elements appear in the bracket expression!
-If the collating sequence includes a
-\fBch\fR
-multi-character collating element,
-then the RE
-\fB[[.ch.]]*c\fR
-matches the first five characters
-of `\fBchchcc\fR',
-and the RE
-\fB[^c]b\fR
-matches all of `\fBchb\fR'.
-.PP
-Within a bracket expression, a collating element enclosed in
-\fB[=\fR
-and
-\fB=]\fR
-is an equivalence class, standing for the sequences of characters
-of all collating elements equivalent to that one, including itself.
-(If there are no other equivalent collating elements,
-the treatment is as if the enclosing delimiters were `\fB[.\fR'\&
-and `\fB.]\fR'.)
-For example, if
-\fBo\fR
-and
-\fB\o'o^'\fR
-are the members of an equivalence class,
-then `\fB[[=o=]]\fR', `\fB[[=\o'o^'=]]\fR',
-and `\fB[o\o'o^']\fR'\&
-are all synonymous.
-An equivalence class may not be an endpoint
-of a range.
-.PP
-Within a bracket expression, the name of a \fIcharacter class\fR enclosed
-in
-\fB[:\fR
-and
-\fB:]\fR
-stands for the list of all characters
-(not all collating elements!)
-belonging to that
-class.
-Standard character class names are:
-.PP
-.RS
-.ne 5
-.nf
-.ta 3c 6c 9c
-\fBalnum	digit	punct
-alpha	graph	space
-blank	lower	upper
-cntrl	print	xdigit\fR
-.fi
-.RE
-.PP
-These stand for the character classes defined in
-\fIctype\fR(3).
-A locale may provide others.
-A character class may not be used as an endpoint of a range.
-.PP
-There are two special cases of bracket expressions:
-the bracket expressions
-\fB[[:<:]]\fR
-and
-\fB[[:>:]]\fR
-are constraints, matching empty strings at
-the beginning and end of a word respectively.
-'\" note, discussion of escapes below references this definition of word
-A word is defined as a sequence of
-word characters
-which is neither preceded nor followed by
-word characters.
-A word character is an
-\fIalnum\fR
-character (as defined by
-\fIctype\fR(3))
-or an underscore
-(\fB_\fR).
-These special bracket expressions are deprecated;
-users of AREs should use constraint escapes instead (see below).
-.SH ESCAPES
-Escapes (AREs only), which begin with a
-\fB\e\fR
-followed by an alphanumeric character,
-come in several varieties:
-character entry, class shorthands, constraint escapes, and back references.
-A
-\fB\e\fR
-followed by an alphanumeric character but not constituting
-a valid escape is illegal in AREs.
-In EREs, there are no escapes:
-outside a bracket expression,
-a
-\fB\e\fR
-followed by an alphanumeric character merely stands for that
-character as an ordinary character,
-and inside a bracket expression,
-\fB\e\fR
-is an ordinary character.
-(The latter is the one actual incompatibility between EREs and AREs.)
-.PP
-Character-entry escapes (AREs only) exist to make it easier to specify
-non-printing and otherwise inconvenient characters in REs:
-.RS 2
-.TP 5
-\fB\ea\fR
-alert, aka bell, character, as in C
-.TP
-\fB\eb\fR
-backspace, as in C
-.TP
-\fB\eB\fR
-synonym for
-\fB\e\fR
-to help reduce backslash doubling in some
-applications where there are multiple levels of backslash processing
-.TP
-\fB\ec\fIX\fR
-(where X is any character) the character whose
-low-order 5 bits are the same as those of
-\fIX\fR,
-and whose other bits are all zero
-.TP
-\fB\ee\fR
-the character whose collating-sequence name
-is `\fBESC\fR',
-or failing that, the character with octal value 033
-.TP
-\fB\ef\fR
-formfeed, as in C
-.TP
-\fB\en\fR
-newline, as in C
-.TP
-\fB\er\fR
-carriage return, as in C
-.TP
-\fB\et\fR
-horizontal tab, as in C
-.TP
-\fB\eu\fIwxyz\fR
-(where
-\fIwxyz\fR
-is exactly four hexadecimal digits)
-the Unicode character
-\fBU+\fIwxyz\fR
-in the local byte ordering
-.TP
-\fB\eU\fIstuvwxyz\fR
-(where
-\fIstuvwxyz\fR
-is exactly eight hexadecimal digits)
-reserved for a somewhat-hypothetical Unicode extension to 32 bits
-.TP
-\fB\ev\fR
-vertical tab, as in C
-are all available.
-.TP
-\fB\ex\fIhhh\fR
-(where
-\fIhhh\fR
-is any sequence of hexadecimal digits)
-the character whose hexadecimal value is
-\fB0x\fIhhh\fR
-(a single character no matter how many hexadecimal digits are used).
-.TP
-\fB\e0\fR
-the character whose value is
-\fB0\fR
-.TP
-\fB\e\fIxy\fR
-(where
-\fIxy\fR
-is exactly two octal digits,
-and is not a
-\fIback reference\fR (see below))
-the character whose octal value is
-\fB0\fIxy\fR
-.TP
-\fB\e\fIxyz\fR
-(where
-\fIxyz\fR
-is exactly three octal digits,
-and is not a
-back reference (see below))
-the character whose octal value is
-\fB0\fIxyz\fR
-.RE
-.PP
-Hexadecimal digits are `\fB0\fR'-`\fB9\fR', `\fBa\fR'-`\fBf\fR',
-and `\fBA\fR'-`\fBF\fR'.
-Octal digits are `\fB0\fR'-`\fB7\fR'.
-.PP
-The character-entry escapes are always taken as ordinary characters.
-For example,
-\fB\e135\fR
-is
-\fB]\fR
-in ASCII,
-but
-\fB\e135\fR
-does not terminate a bracket expression.
-Beware, however, that some applications (e.g., C compilers) interpret 
-such sequences themselves before the regular-expression package
-gets to see them, which may require doubling (quadrupling, etc.) the `\fB\e\fR'.
-.PP
-Class-shorthand escapes (AREs only) provide shorthands for certain commonly-used
-character classes:
-.RS 2
-.TP 10
-\fB\ed\fR
-\fB[[:digit:]]\fR
-.TP
-\fB\es\fR
-\fB[[:space:]]\fR
-.TP
-\fB\ew\fR
-\fB[[:alnum:]_]\fR
-(note underscore)
-.TP
-\fB\eD\fR
-\fB[^[:digit:]]\fR
-.TP
-\fB\eS\fR
-\fB[^[:space:]]\fR
-.TP
-\fB\eW\fR
-\fB[^[:alnum:]_]\fR
-(note underscore)
-.RE
-.PP
-Within bracket expressions, `\fB\ed\fR', `\fB\es\fR',
-and `\fB\ew\fR'\&
-lose their outer brackets,
-and `\fB\eD\fR', `\fB\eS\fR',
-and `\fB\eW\fR'\&
-are illegal.
-.PP
-A constraint escape (AREs only) is a constraint,
-matching the empty string if specific conditions are met,
-written as an escape:
-.RS 2
-.TP 6
-\fB\eA\fR
-matches only at the beginning of the string
-(see MATCHING, below, for how this differs from `\fB^\fR')
-.TP
-\fB\em\fR
-matches only at the beginning of a word
-.TP
-\fB\eM\fR
-matches only at the end of a word
-.TP
-\fB\ey\fR
-matches only at the beginning or end of a word
-.TP
-\fB\eY\fR
-matches only at a point which is not the beginning or end of a word
-.TP
-\fB\eZ\fR
-matches only at the end of the string
-(see MATCHING, below, for how this differs from `\fB$\fR')
-.TP
-\fB\e\fIm\fR
-(where
-\fIm\fR
-is a nonzero digit) a \fIback reference\fR, see below
-.TP
-\fB\e\fImnn\fR
-(where
-\fIm\fR
-is a nonzero digit, and
-\fInn\fR
-is some more digits,
-and the decimal value
-\fImnn\fR
-is not greater than the number of closing capturing parentheses seen so far)
-a \fIback reference\fR, see below
-.RE
-.PP
-A word is defined as in the specification of
-\fB[[:<:]]\fR
-and
-\fB[[:>:]]\fR
-above.
-Constraint escapes are illegal within bracket expressions.
-.PP
-A back reference (AREs only) matches the same string matched by the parenthesized
-subexpression specified by the number,
-so that (e.g.)
-\fB([bc])\e1\fR
-matches
-\fBbb\fR
-or
-\fBcc\fR
-but not `\fBbc\fR'.
-The subexpression must entirely precede the back reference in the RE.
-Subexpressions are numbered in the order of their leading parentheses.
-Non-capturing parentheses do not define subexpressions.
-.PP
-There is an inherent historical ambiguity between octal character-entry 
-escapes and back references, which is resolved by heuristics,
-as hinted at above.
-A leading zero always indicates an octal escape.
-A single non-zero digit, not followed by another digit,
-is always taken as a back reference.
-A multi-digit sequence not starting with a zero is taken as a back 
-reference if it comes after a suitable subexpression
-(i.e. the number is in the legal range for a back reference),
-and otherwise is taken as octal.
-.SH "METASYNTAX"
-In addition to the main syntax described above, there are some special
-forms and miscellaneous syntactic facilities available.
-.PP
-Normally the flavor of RE being used is specified by
-application-dependent means.
-However, this can be overridden by a \fIdirector\fR.
-If an RE of any flavor begins with `\fB***:\fR',
-the rest of the RE is an ARE.
-If an RE of any flavor begins with `\fB***=\fR',
-the rest of the RE is taken to be a literal string,
-with all characters considered ordinary characters.
-.PP
-An ARE may begin with \fIembedded options\fR:
-a sequence
-\fB(?\fIxyz\fB)\fR
-(where
-\fIxyz\fR
-is one or more alphabetic characters)
-specifies options affecting the rest of the RE.
-These supplement, and can override,
-any options specified by the application.
-The available option letters are:
-.RS 2
-.TP 3
-\fBb\fR
-rest of RE is a BRE
-.TP 3
-\fBc\fR
-case-sensitive matching (usual default)
-.TP 3
-\fBe\fR
-rest of RE is an ERE
-.TP 3
-\fBi\fR
-case-insensitive matching (see MATCHING, below)
-.TP 3
-\fBm\fR
-historical synonym for
-\fBn\fR
-.TP 3
-\fBn\fR
-newline-sensitive matching (see MATCHING, below)
-.TP 3
-\fBp\fR
-partial newline-sensitive matching (see MATCHING, below)
-.TP 3
-\fBq\fR
-rest of RE is a literal (``quoted'') string, all ordinary characters
-.TP 3
-\fBs\fR
-non-newline-sensitive matching (usual default)
-.TP 3
-\fBt\fR
-tight syntax (usual default; see below)
-.TP 3
-\fBw\fR
-inverse partial newline-sensitive (``weird'') matching (see MATCHING, below)
-.TP 3
-\fBx\fR
-expanded syntax (see below)
-.RE
-.PP
-Embedded options take effect at the
-\fB)\fR
-terminating the sequence.
-They are available only at the start of an ARE,
-and may not be used later within it.
-.PP
-In addition to the usual (\fItight\fR) RE syntax, in which all characters are
-significant, there is an \fIexpanded\fR syntax,
-available in all flavors of RE
-with the \fB-expanded\fR switch, or in AREs with the embedded x option.
-In the expanded syntax,
-white-space characters are ignored
-and all characters between a
-\fB#\fR
-and the following newline (or the end of the RE) are ignored,
-permitting paragraphing and commenting a complex RE.
-There are three exceptions to that basic rule:
-.RS 2
-.PP
-a white-space character or `\fB#\fR' preceded by `\fB\e\fR' is retained
-.PP
-white space or `\fB#\fR' within a bracket expression is retained
-.PP
-white space and comments are illegal within multi-character symbols
-like the ARE `\fB(?:\fR' or the BRE `\fB\e(\fR'
-.RE
-.PP
-Expanded-syntax
-white-space characters are blank, tab, newline, etc. (any character
-defined as \fIspace\fR by
-\fIctype\fR(3)).
-Exactly how a multi-line expanded-syntax RE
-can be entered interactively by a user,
-if at all, is application-specific;
-expanded syntax is primarily a scripting facility.
-.PP
-Finally, in an ARE,
-outside bracket expressions, the sequence `\fB(?#\fIttt\fB)\fR'
-(where
-\fIttt\fR
-is any text not containing a `\fB)\fR')
-is a comment,
-completely ignored.
-Again, this is not allowed between the characters of
-multi-character symbols like `\fB(?:\fR'.
-Such comments are more a historical artifact than a useful facility,
-and their use is deprecated;
-use the expanded syntax instead.
-.PP
-\fINone\fR of these metasyntax extensions is available if the application
-(or an initial
-\fB***=\fR
-director)
-has specified that the user's input be treated as a literal string
-rather than as an RE.
-.SH MATCHING
-In the event that an RE could match more than one substring of a given
-string,
-the RE matches the one starting earliest in the string.
-If the RE could match more than one substring starting at that point,
-its choice is determined by its \fIpreference\fR:
-either the longest substring, or the shortest.
-.PP
-Most atoms, and all constraints, have no preference.
-A parenthesized RE has the same preference (possibly none) as the RE.
-A quantified atom with quantifier
-\fB{\fIm\fB}\fR
-or
-\fB{\fIm\fB}?\fR
-has the same preference (possibly none) as the atom itself.
-A quantified atom with other normal quantifiers (including
-\fB{\fIm\fB,\fIn\fB}\fR
-with
-\fIm\fR
-equal to
-\fIn\fR)
-prefers longest match.
-A quantified atom with other non-greedy quantifiers (including
-\fB{\fIm\fB,\fIn\fB}?\fR
-with
-\fIm\fR
-equal to
-\fIn\fR)
-prefers shortest match.
-A branch has the same preference as the first quantified atom in it
-which has a preference.
-An RE consisting of two or more branches connected by the
-\fB|\fR
-operator prefers longest match.
-.PP
-Subject to the constraints imposed by the rules for matching the whole RE,
-subexpressions also match the longest or shortest possible substrings,
-based on their preferences,
-with subexpressions starting earlier in the RE taking priority over
-ones starting later.
-Note that outer subexpressions thus take priority over
-their component subexpressions.
-.PP
-Note that the quantifiers
-\fB{1,1}\fR
-and
-\fB{1,1}?\fR
-can be used to force longest and shortest preference, respectively,
-on a subexpression or a whole RE.
-.PP
-Match lengths are measured in characters, not collating elements.
-An empty string is considered longer than no match at all.
-For example,
-\fBbb*\fR
-matches the three middle characters of `\fBabbbc\fR',
-\fB(week|wee)(night|knights)\fR
-matches all ten characters of `\fBweeknights\fR',
-when
-\fB(.*).*\fR
-is matched against
-\fBabc\fR
-the parenthesized subexpression
-matches all three characters, and
-when
-\fB(a*)*\fR
-is matched against
-\fBbc\fR
-both the whole RE and the parenthesized
-subexpression match an empty string.
-.PP
-If case-independent matching is specified,
-the effect is much as if all case distinctions had vanished from the
-alphabet.
-When an alphabetic that exists in multiple cases appears as an
-ordinary character outside a bracket expression, it is effectively
-transformed into a bracket expression containing both cases,
-so that
-\fBx\fR
-becomes `\fB[xX]\fR'.
-When it appears inside a bracket expression, all case counterparts
-of it are added to the bracket expression, so that
-\fB[x]\fR
-becomes
-\fB[xX]\fR
-and
-\fB[^x]\fR
-becomes `\fB[^xX]\fR'.
-.PP
-If newline-sensitive matching is specified,
-\fB.\fR
-and bracket expressions using
-\fB^\fR
-will never match the newline character
-(so that matches will never cross newlines unless the RE
-explicitly arranges it)
-and
-\fB^\fR
-and
-\fB$\fR
-will match the empty string after and before a newline
-respectively, in addition to matching at beginning and end of string
-respectively.
-ARE
-\fB\eA\fR
-and
-\fB\eZ\fR
-continue to match beginning or end of string \fIonly\fR.
-.PP
-If partial newline-sensitive matching is specified,
-this affects
-\fB.\fR
-and bracket expressions
-as with newline-sensitive matching, but not
-\fB^\fR
-and `\fB$\fR'.
-.PP
-If inverse partial newline-sensitive matching is specified,
-this affects
-\fB^\fR
-and
-\fB$\fR
-as with
-newline-sensitive matching,
-but not
-\fB.\fR
-and bracket expressions.
-This isn't very useful but is provided for symmetry.
-.SH "LIMITS AND COMPATIBILITY"
-No particular limit is imposed on the length of REs.
-Programs intended to be highly portable should not employ REs longer
-than 256 bytes,
-as a POSIX-compliant implementation can refuse to accept such REs.
-.PP
-The only feature of AREs that is actually incompatible with
-POSIX EREs is that
-\fB\e\fR
-does not lose its special
-significance inside bracket expressions.
-All other ARE features use syntax which is illegal or has
-undefined or unspecified effects in POSIX EREs;
-the
-\fB***\fR
-syntax of directors likewise is outside the POSIX
-syntax for both BREs and EREs.
-.PP
-Many of the ARE extensions are borrowed from Perl, but some have
-been changed to clean them up, and a few Perl extensions are not present.
-Incompatibilities of note include `\fB\eb\fR', `\fB\eB\fR',
-the lack of special treatment for a trailing newline,
-the addition of complemented bracket expressions to the things
-affected by newline-sensitive matching,
-the restrictions on parentheses and back references in lookahead constraints,
-and the longest/shortest-match (rather than first-match) matching semantics.
-.PP
-The matching rules for REs containing both normal and non-greedy quantifiers
-have changed since early beta-test versions of this package.
-(The new rules are much simpler and cleaner,
-but don't work as hard at guessing the user's real intentions.)
-.PP
-Henry Spencer's original 1986 \fIregexp\fR package,
-still in widespread use (e.g., in pre-8.1 releases of Tcl),
-implemented an early version of today's EREs.
-There are four incompatibilities between \fIregexp\fR's near-EREs
-(`RREs' for short) and AREs.
-In roughly increasing order of significance:
-.PP
-.RS
-In AREs,
-\fB\e\fR
-followed by an alphanumeric character is either an
-escape or an error,
-while in RREs, it was just another way of writing the 
-alphanumeric.
-This should not be a problem because there was no reason to write
-such a sequence in RREs.
-.PP
-\fB{\fR
-followed by a digit in an ARE is the beginning of a bound,
-while in RREs,
-\fB{\fR
-was always an ordinary character.
-Such sequences should be rare,
-and will often result in an error because following characters
-will not look like a valid bound.
-.PP
-In AREs,
-\fB\e\fR
-remains a special character within `\fB[\|]\fR',
-so a literal
-\fB\e\fR
-within
-\fB[\|]\fR
-must be written `\fB\e\e\fR'.
-\fB\e\e\fR
-also gives a literal
-\fB\e\fR
-within
-\fB[\|]\fR
-in RREs,
-but only truly paranoid programmers routinely doubled the backslash.
-.PP
-AREs report the longest/shortest match for the RE,
-rather than the first found in a specified search order.
-This may affect some RREs which were written in the expectation that
-the first match would be reported.
-(The careful crafting of RREs to optimize the search order for fast
-matching is obsolete (AREs examine all possible matches
-in parallel, and their performance is largely insensitive to their
-complexity) but cases where the search order was exploited to deliberately 
-find a match which was \fInot\fR the longest/shortest will need rewriting.)
-.RE
-
-.SH "BASIC REGULAR EXPRESSIONS"
-BREs differ from EREs in several respects.  `\fB|\fR', `\fB+\fR',
-and
-\fB?\fR
-are ordinary characters and there is no equivalent
-for their functionality.
-The delimiters for bounds are
-\fB\e{\fR
-and `\fB\e}\fR',
-with
-\fB{\fR
-and
-\fB}\fR
-by themselves ordinary characters.
-The parentheses for nested subexpressions are
-\fB\e(\fR
-and `\fB\e)\fR',
-with
-\fB(\fR
-and
-\fB)\fR
-by themselves ordinary characters.
-\fB^\fR
-is an ordinary character except at the beginning of the
-RE or the beginning of a parenthesized subexpression,
-\fB$\fR
-is an ordinary character except at the end of the
-RE or the end of a parenthesized subexpression,
-and
-\fB*\fR
-is an ordinary character if it appears at the beginning of the
-RE or the beginning of a parenthesized subexpression
-(after a possible leading `\fB^\fR').
-Finally,
-single-digit back references are available,
-and
-\fB\e<\fR
-and
-\fB\e>\fR
-are synonyms for
-\fB[[:<:]]\fR
-and
-\fB[[:>:]]\fR
-respectively;
-no other escapes are available.
+.SH "SEE ALSO"
+re_syntax(n)
 
-.VE 8.1
 .SH KEYWORDS
 match, regular expression, string
diff --git a/doc/regsub.n b/doc/regsub.n
index 516a417..65c22a6 100644
--- a/doc/regsub.n
+++ b/doc/regsub.n
@@ -5,7 +5,7 @@
 '\" See the file "license.terms" for information on usage and redistribution
 '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 '\" 
-'\" RCS: @(#) $Id: regsub.n,v 1.2 1998/09/14 18:39:54 stanton Exp $
+'\" RCS: @(#) $Id: regsub.n,v 1.3 1999/06/24 21:15:13 jpeek Exp $
 '\" 
 .so man.macros
 .TH regsub n 7.4 Tcl "Tcl Built-In Commands"
@@ -23,6 +23,8 @@ This command matches the regular expression \fIexp\fR against
 \fIstring\fR,
 and it copies \fIstring\fR to the variable whose name is
 given by \fIvarName\fR.
+(Regular expression matching is described in the \fBre_syntax\fR
+reference page.)
 If there is a match, then while copying \fIstring\fR to \fIvarName\fR
 the portion of \fIstring\fR that
 matched \fIexp\fR is replaced with \fIsubSpec\fR.
diff --git a/doc/switch.n b/doc/switch.n
index 503a5ba..fb7ac60 100644
--- a/doc/switch.n
+++ b/doc/switch.n
@@ -5,7 +5,7 @@
 '\" See the file "license.terms" for information on usage and redistribution
 '\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 '\" 
-'\" RCS: @(#) $Id: switch.n,v 1.2 1998/09/14 18:39:55 stanton Exp $
+'\" RCS: @(#) $Id: switch.n,v 1.3 1999/06/24 21:15:14 jpeek Exp $
 '\" 
 .so man.macros
 .TH switch n 7.0 Tcl "Tcl Built-In Commands"
@@ -47,7 +47,7 @@ When matching \fIstring\fR to the patterns, use glob-style matching
 \fB\-regexp\fR
 When matching \fIstring\fR to the patterns, use regular
 expression matching
-(i.e. the same as implemented by the \fBregexp\fR command).
+(as described in the \fBre_syntax\fR reference page).
 .TP 10
 \fB\-\|\-\fR
 Marks the end of options.  The argument following this one will
-- 
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