SYSML2 — The derivation of AssignmentActionUsage::referent is wrong

In the SysML Specification, 8.3.16.5 AssignmentActionUsage, the constraint deriveAssignmentActionUsageReferent states that "The referent of an AssignmentActionUsage is the first Feature that is the memberElement of a ownedMembership that is not an OwningMembership." However, according to the BNF in 8.2.2.16.5 Assignment Action Usages, the intended referent of an assignment is parsed as a FeatureChainMember, and, for an actual chain of more than one Feature, the chaining Feature is owned by the AssignmentActionUsage via OwningMembership. Therefore, it will not be identified as the referent of the assignment according to the current derivation.

Correct the derivation

The constraint deriveAssignmentActionUsageReferent should be changed to replace OwningMembership with FeatureMembership. In addition, the constraint validateAssignmentActionUsageReferent added in the approved resolution of SYSML2-28 should be similarly revised. Finally, the BNF production OwnedFeatureChainMember in 8.2.2.16.5 Assignment Action Usages incorrectly has a result OwnedMembership which should be OwningMembership.