A.2.1:4.3 - Occurrence Identity

An occurrence of a declared species begins when that species’ direct predicate starts obtaining for fixed participant values. It continues over the maximal uninterrupted predicate-true interval. It ends when a participant changes or the predicate ceases to obtain. A later resumption is another occurrence even when every participant value is the same.

A context field ending in ...SystemRoleAssignmentRef uses U.RelationRef constrained to U.SystemRoleAssignment and resolves to the exact occurrence while keeping its declared species recoverable.

An assignment assertion or occurrence description can state assignmentInterval with a temporal reference, start, end or explicit open end, and continuity claim. Closing an open interval later refines the same description when world-side obtaining was uninterrupted. When evidence is missing, whether the assignment obtained remains unknown; the evidence gap by itself establishes neither continuity nor a split. The occurrence ends when its predicate ceases to obtain; evidence of cessation supports a conclusion about when it ended.

Keep ordinary interval content here. When a positive temporal aspect itself becomes a relied-on object—its temporal reference, validity or currentness window, duration, cadence, rhythm, or interval structure—use C.27.TA for that aspect and keep the assignment occurrence separate. Use C.27 only for the different question of whether a temporal claim is adequate.

Taxonomy, scheme, KindSignature, assertion, interval description, and selected publication form can be cited when they matter to interpretation or evidence. Only the species’ declared participants and predicate determine world-side occurrence identity.