2.2.2.2.

If using an internal time zone list that can be changed, a versioning of the TZID could be used allowing different versions of the same TZIDs to be kept. This would allow applications to have events using different time zones with the same TZID. Take note however that consuming and preserving all time zones can become quite problematic:

• Since time zone ids are often shown to users, the time zone list could become quite large and confusing over time.

• The need to “preserve” the original consumed time zone can also look like a bad idea when a time zone rule changes; meetings that have yet to occur will most likely need to be updated with the new time zone rule.