Purpose: to collect a variety of commonly used phrases, often referred to within the Tcl community as mantras relating to Tcl.
be prepared recruit a developer (or gird your loins for battle) and submit a TIP providing details of what s/he plans to do to add functionality in the core, and be prepared to discuss/debate/argue your case.
as possible, cross platform across at least Unix-like, Windows, and to a lesser degree MacOS, VMS, etc. Platform specific functions go into extensions, with those potentially being wrapped up into the same tar file as libtcl code.
specific applications need a new feature - not to create a single library containing every imaginable function that every programmer since the beginning of the computer age ever needed. Developers should work on becoming more comfortable using existing extensions or writing their own rather than expecting an all in one language.