Platonic realism satisfies one of those constraints, in that it is a theory of what general terms refer to. "Forms" are ideal in supplying meaning to referents for general terms. That is, to understand terms such as "applehood" and "redness", Platonic realism says that they refer to forms. Indeed, Platonism gets much of its plausibility because mentioning "redness", for example, could be assumed to be referring to something that is apart from space and time, but which has many specific instances.