UAF13 — 'Usage of + 'Whole:Part' - ProtocolLayer is Not a Distinct Metamodel Concept - It is a Reflexive Whole:Part Relationship on Protocol

9.1.10 Domain Metamodel::Standards::Structure , Fig 9:236 ProtocolLayer

ProtocolLayer is defined as 'Usage of a Protocol in the context of another Protocol. Creates a whole-part relationship.'

1) ProtocolLayer (as identified by 'another' and 'usage') is not therefore distinct from Protocol and shouldn't therefore be a metamodel element - it should be represented by a whole:part relationship on Protocol.

2) ProtocolLayer is not a type of Protocol - which I what I think the incorrect role name on the Association from ProtocolLayer to Protocol is stating. whole:part + type = ?

3) Any metamodel element including 'usage' is likely to be invalid. Usage is a particular UML implementation and often a fudge. No metamodel element is a usage of any other. An elementis its own thing - if usage is involved it is not a distinct concept.