SCTE 104/35 Codex

Every SCTE 35 message tied to one splice event shares a common event id: the splice_event_id in splice_insert and splice_schedule, and the segmentation_event_id carried in a segmentation_descriptor on a time_signal. That shared id is what lets a receiver group repeats, updates, and the eventual end into a single event. An id may be reused once its event has ended, whether by an explicit end or cancel message or by exhausting the signaled duration (SCTE 67 clauses 7.4 and 10.6, and SCTE 35 clause 10.3.3.7). A related caveat is a reporting concern rather than an id-lifetime rule: when a segment's duration elapses without its expected end message, the segment is treated as unclosed for reporting even though its id is already free to reuse, and inferring an end from elapsed duration alone is discouraged. Because ids can come from several points in the chain (source material, uplink triggers, headend triggers), collisions are a real risk, so each insertion point needs its own id space to keep values from clashing.