Comments
It's not clear, when one requests a value set resource, whether one should expect the definition or the expansion.
There seem to be different use cases for this resource. One is an implementer needing codes, in which case we'd want to provide an expansion (a la CTS2 "resolvedValueSet").
Another is a service needing a definition, in which case we'd want to provide either a define or a compose--however the VS is defined.
But I need to be able to specify which one I want, which seems to me to suggest that the Definition and the Expansion should be different resources.
(As would be the validation resource – validityOfCodeAlphaInValueSetBetaAtTimeT)

Grahame's Comments
agree to make this difference more explicit in the value set scope (refer to terminology service) and also more explicit in the terminology service API too