Some parts of the RFC refer to stuff such as labels and aliases but also to sitelinks. The later is Item specific. Does that mean these modules are only supposed to support Items? What about Properties or Queries?
Topic on Talk:Requests for comment/Wikidata API
It was decided to let the current wbeditentity address the items this way even if it doesn't match up with properties and queries. I'm tempted to say that we should drop this addressing (that is sitelink) for all modules that sets something. It sort of makes sense for wbgetentities, but why would an external party not know the real identity of the item?
We could go two routes - have two or more independent properties - one that would have all common values found in items, properties, and queries; and other props that have item specific or query specific ones.
Or, we could have one prop for all that would work for all, and return the data relevant based on the type of page. I am inclined to go with the second route as it would be much easier to implement and allow less DB queries, without causing too much confusion by the API users.