Changes to Tcl between r3 and r4
'''Tool Command Language'''
Tcl is a dynamic programming language that is available on many platforms.
Some links:
* http://www.tcl.tk/
* http://wiki.tcl.tk/
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'''Tcl Documentation'''
* Tcl Cheat Sheet [http://home.houston.rr.com/brianohagan/tcl_tk_ref_guide.html] [http://www.rkeene.org/projects/info/resources/tcl/docs/tcl-tk-reference-guide.pdf]
* Tcl Cheat Sheet [http://home.houston.rr.com/brianohagan/tcl_tk_ref_guide.html] (PDF [http://www.rkeene.org/projects/info/resources/tcl/docs/tcl-tk-reference-guide.pdf])
Legend
Only in r3
Only in r4 --> Modified slightly between r3 and r4