BPMN21 — Allowable start events for event sub-process inconsistently defined

There is an apparent conflict in the specification concerning the permissible Start Event types for an Event Sub-Process.

On Page 174, the specification states: "The Start Event of an Event Sub-Process MUST have a defined trigger. The Start Event trigger (EventDefinition) MUST be from the following types: Message, Error, Escalation, Compensation, Conditional, Signal, and Multiple." This enumeration excludes the Timer and Parallel event types.

This specification appears inconsistent with the restriction on Page 241, which additionally allows Timer and Parallel event types for the Start Event: "A Start Event can also initiate an inline Event Sub-Process (see page 174). In that case, the same Event types as for boundary Events are allowed (see Table 10.86), namely: Message, Timer, Escalation, Error, Compensation, Conditional, Signal, Multiple, and Parallel."

It is consequently unclear whether Timer and Parallel events may be the Start Event in an Event Sub-Process.