The rebasing tool "stamps" calendar items as having been re-based, so subsequent re-runs of the rebasing tool won't move the same calendar item twice. What is the object property/value that is set to indicate the object has been re-based?

Q: the rebasing tool "stamps" calendar items as having been re-based, so subsequent re-runs of the rebasing tool won't move the same calendar item twice. What is the object property/value that is set to indicate the object has been re-based?
A: The property is a named property on the calendar object. It is not a simple flag - it is a time zone definition structure so that future readers will know what time zone rules were used to generate the GMT times by which single instance items are stored.