Vzic is a program to convert the Olson timezone database files into VTIMEZONE files compatible with the iCalendar specification (RFC2445).
(The name is based on the 'zic' program which converts the Olson files into time zone information files used by several Unix C libraries, including glibc. See zic(8) and tzfile(5).)
You need the Olson timezone database files, which can be found at:
ftp://elsie.nci.nih.gov/pub/
(Old versions can be found at ftp://munnari.oz.au/pub/oldtz/)
Vzic also uses the GLib library (for hash tables, dynamic arrays, and date calculations). You need version 2.0 or higher. You can get this from:
http://www.gtk.org
Vzic can generate 'pure' timezone files which match the Olson timezone data exactly, or it can generate timezone files that are compatable with Microsoft Outlook (which is the default).
The timezone files generated by Vzic have been thoroughly tested against the Unix timezone data and no errors have been found. (Note that this doesn't mean the data is perfect - the Olson data itself may be wrong, or may be out-of-date. The timezone data is updated frequently.)