[tz] VTIMEZONEs and Outlook

All, Sorry for the off-topic post, but I'm fishing. I'm one of the maintainers of vzic, a utility to convert IANA tzdata into iCalendar VTIMEZONE components.  In the process of tweaking the tool to handle recent tzdata changes and to generate more correct/compact VTIMEZONEs in "pure" mode, I managed to break the generation of Outlook-compatible VTIMEZONEs. Does anyone know what parts of the iCalendar/VTIMEZONE spec that Outlook doesn't properly handle and/or know what the requirements are to be compatible with Outlook? -- Ken Murchison Cyrus Development Team Fastmail US LLC