Package cmdline is a part of Tcllib. Documentation can be read online at http://tcllib.sourceforge.net/doc/cmdline.html , and examples of cmdline usage appear in ftpd, htmlparse, and pop3.
Glenn Jackman offers http://groups.google.com/groups?th=89144039acd5554b#link5 and http://groups.google.com/groups?th=84e714d1329a035#link5 as "examples of cmdline in action".
The cmdline package can be used for both programs which accept arguments via the argv list as well as procs which have specific needs for argument processing.
Category Package, a subset of Tcllib.