Topic↝Identity, with a governing noun in the domain of communication or cognition:
Something may be specified with a category in order to disambiguate it #001, or to provide an interpretation or frame of reference with which that entity is to be considered. In some cases, like #009, the category is a shell noun (Schmid, 2000) requiring further specification.
Categorizations may be situational rather than permanent/definitional:
Paraphrase test: “(thing) IS (category) [in the context of the event]”: “Washington is a liberal state”, “opening a new business is a hassle”, “She is Ophelia”, etc. Note that as+category may attach syntactically to a verb, as in #004 and #011, rather than being governed by the item it describes.
If the object of the preposition is a property (as opposed to a category), the scene role is Characteristic:
Secondary predicate adjective: Characteristic↝Identity
See also: ComparisonRef
A category being ascribed to something, or something belonging to the category denoted by the governor.