SYSMOAS — DataVersion::payload multiplicity

In the Project Data Versioning PIM (Sec 7.1.2, Fig. 5), the relationship between DataVersion and its payload Data is inconsistent with the representation of deletion in Commits.

As per page 71, Commit::change "is the set of DataVersion records representing Data that is created, updated, or deleted in the
Commit". This implies that Data being deleted by the Commit must be expressed as a DataVersion object somehow.

The approach followed by the JSON/RPC PSM is that the DataVersion has an identity that identifies the Data, but the payload is null. However, in the PIM, the multiplicity of DataVersion::payload does not allow it to be null. So seemingly the PIM cannot actually express a Commit that deletes things.