 There is generally taken to be a difference in ontological commitment between parameters of evaluation on the one hand and semantic values of referential terms and implicit arguments of predicates on the other. It is generally understood that parameters of evaluation do not involve an ontological commitment on the part of the language user, but are mere posits in the semantic theory, which means they have a status as entities only in the semantic metalanguage. Parameters of evaluation involve an ontological commitment on the part of the language users only if there are referential expression in the object language making reference to them, or so the general view appears to be. For example, there are referential expressions in English referring to times (today, that day, that moment, etc), but not those referring to worlds, at least not from the core of language  (§4.1).  Frege’s criterion of objecthood of course does not apply to parameters of evaluation (and, in fact, it did not even apply to implicit arguments).