TIP is the acronym for Tcl Improvement Proposal, a process put into place by the Tcl Core Team (TCT) for submitting changes to Tcl or Tk which would result in C API or script level API interfaces.
All existing TIPs can be found at http://www.purl.org/tcl/tip/ , with backup at http://www.cs.man.ac.uk/fellowsd-bin/TIP/ .
Votes require (an) implementation (plan).
A SourceForge "Feature Request" ?? is a lighter-weight entry point for people with clearer ideas about needs than implementation.
One possible ideal: TCT does as little as possible with TIPs. That is, TCT supervises/manages/oversees the process. Engineering work shouldn't be a TCT responsibility (in general? sometimes? ...).