http://tcl.tk/man/tcl8.4/UserCmd/wish.htm
wish is a simple Tcl/Tk application created during the build process of Tk. It has minimal functionality other than reading files and attempting to execute the Tcl commands inside. It does perform an implicit package require Tk as well as drop the user into an event loop.
People writing scripts to be loaded from the wish command line should be aware that \u001a is an end-of-file character in scripts.