OCL25 — Vagueness about meaning of 0..1 multiplicity in OCL and UML

UML-alignment of OCL type signatures
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Following discussion in the "Vagueness about meaning of 0..1 multiplicity in OCL and UML" threads
of the UML2 and OCL RTFs the following problems exist in alignment of the UML and OCL type systems.

The OCL specification does not provide a clear description of the comparative semantics of for instance
Integer[1] and Integer[0..1].

The Complete OCL syntax for an Operation Context Declaration uses OCL type decalarations and so
fails to provide the same expressivity as a UML operation declaration with multiplicities.

Suggest:

a) a clear indication that

An Integer[1] may have integer values, null or invalid, of which only integer values are well-formed.

An Integer[0..1] may have integer values, null or invalid, of which integer values and null are well-formed.

b) an enhancement to the type declaration syntax to allow

Integer[0..1] or Integer[1] to indicate a nullable/non-nullable value.

Set(Integer[1..7]) to capture the expressivity of a UML multiplicity