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+The source code for Tcl is managed by fossil.  Tcl developers coordinate all
+changes to the Tcl source code at
+
+> [Tcl Source Code](https://core.tcl-lang.org/tcl/timeline)
+
+Release Tcl 8.7b1 arises from the check-in with tag core-8.7-b1.
+
+Highlighted differences between Tcl 8.7 and Tcl 8.6 are summarized below,
+with focus on changes important to programmers using the Tcl library and
+writing Tcl scripts.
+
+## Internationalization of text
+ - Full Unicode range of codepoints
+ - New encodings: utf-16/utf-32/ucs-2(le|be), CESU-8, etc.
+ - `encoding` options -profile, -failindex manage encoding of I/O.
+ - `msgcat` supports custom locale search list
+ - `source` defaults to -encoding utf-8
+
+## Zip filesystems and attached archives.
+
+## Unix notifiers available using epoll() or kqueue()
+ - relieves limits on file descriptors imposed by legacy select()
+
+## Notable incompatibilities
+ - No --disable-threads build option.  Always thread-enabled.
+ - Windows platform needs Windows 7 or Windows Server 2008 R2 or later
+
+## New commands
+ - `array default`, `array for`
+ - `coroinject`, `coroprobe`
+ - `clock add weekdays`
+ - `dict getdefault`
+ - `file tempdir`, `file home`, `file tildeexpand`
+ - `info commandtype`
+ - `ledit`
+ - `lpop`
+ - `lremove`
+ - `lseq`
+ - `package files`
+ - `string insert`, `string is dict`
+ - `tcl::process`
+ - `*::build-info`
+
+## New command options
+ - `regsub ... -command ...`
+ - `lsearch ... -stride ...`
+ - `clock scan ... -validate ...`
+ - `socket ... -nodelay ... -keepalive ...`
+ - `vwait` controlled by several new options
+
+## Numbers
+ - 0dNNNN format to compel decimal interpretation.
+ - NN_NNN_NNN, underscores in numbers for optional readability
+ - Functions: isinf() isnan() isnormal() issubnormal() isunordered()
+ - `fpclassify`
+ - Function int() no longer truncates to word size
+
+## tcl::oo facilities
+ - private variable and methods
+ - `method -export`, `method -unexport`
+