Is the IfcWorkSchedule project declaration mutually exclusive to aggregation within a relating IfcWorkPlan?

Originally posted https://forums.buildingsmart.org/t/is-the-ifcworkschedule-project-declaration-mutually-exclusive-to-aggregation-within-a-relating-ifcworkplan/3510

The IFC documentation describes two possible relationships on how an IfcWorkSchedule is related back to the IfcProject / IfcContext.

One scenario is that the IfcWorkSchedule is directly declared to the project.


Another scenario is that the IfcWorkSchedule is aggregated to an IfcWorkPlan, and the IfcWorkPlan is then declared to the project.


There are two potential interpretations:

1. An IfcWorkSchedule is **always** declared to the IfcContext, and may be additionally included as an aggregate to an IfcWorkPlan.
2. An IfcWorkSchedule is declared to the IfcContext, **unless** it is included as an aggregate to an IfcWorkPlan

Can someone clarify?