See issue 438, also from the IRC, and taking the oposite position. Gluons provide a means for schedule and re-use of Sequences during service interactions. Additioanal language was added in setion 3.1.2 to make this clearer. An Interval is a unit of time, and can be bound to service delivery. An Unscheduled Interval has no specified date and time. A Scheduled Interval has a specified start date and time. Intervals can legally contain all elements properties as defined in [RFC5545] . For convenience, the elements essential to coordinating service operations using Intervals are listed in Table 3-1. An Interval is part of a Sequence. An entire Sequence can be scheduled by scheduling a single Interval in a Sequence. A single Sequence can be scheduled multiple times through repeated reference by different Gluons. For this reason, of the three primary temporal elements (dtStart, dtEnd, and Duration) in a Component, the Duration has primacy in Intervals. Within a Sequence, a maximum of a single Interval MAY have a dtStart or a dtEnd.