regarding object and target having a domain of Activity, my suggestion was/is to define new properties specific to the stamp object and its QuoteAuthorization type. there's no real reason to stick to AS2 Vocab here. if you were to reuse AS2 Vocab then the only properties applicable are context (signaling purpose) and inReplyTo (signaling response). this technically works in a semantic sense, but only in a broad general sense. "the authorization stamp exists in context of the quoted post, and it is a response to the quote post."the more specific way to describe it is to instead define something like authorizationOf and authorizationScope or whatever names you wanted to bikeshed.