The Recurrence functionality for Vavailability (in AvailabilityType) should also be available for Gluons.
A RecurrenceType class containing RRules, Exdate, and Rdate as RFC5545 conformed strings is also needed for reuse - in GluonType and AvailableType.
Note that WD14 AvailableType does NOT have Rdate.
Descriptive rules for inheritance of RecurrenceType need to be created. I suggest that RecurrenceType inheritance shall not cross the Gluon-Interval boundary; replacement rather than logical operations seems much simpler to process.