 Since the criterion for distinguishing linguistic expressions is based on ontological differences among their significata, Burley’s semantic system includes a third kind of expression falling between the simple and the complex. These are concrete accidental terms (such as ‘white’ or ‘father’), whose significata are not absolutely simple but not exactly complex either. Quite often in the middle (ed. Conti, pp. 12, 14–15, 19, 33, 38, 60, 78) and final commentaries on the Categories (chs. de sufficientia praedicamentorum, fol. 21ra; de substantia, fol. 24rb; de relatione, fol. 34rb; see also LsP, ch. de ubi, fol. 59vb) he affirms that instead of signifying simple objects, concrete accidental terms signify aggregates of substance along with the accidental form primarily signified by the term itself. Such aggregates are lacking in numerical unity and hence do not fall under any of the ten categories; they are not properly beings (entia). For this reason, although concrete accidental terms are not simple from a grammatical point of view, they do not count as names (TsP, ch. de subiecto et praedicato, ed. Conti, pp. 19–20; EP, chs. de relatione, fol. 37ra–b; de qualitate, fol. 41rb). The metaphysical constituents of such aggregates (substance and accidental form) are related to the concrete accidental term in different ways: on the one hand, the form is the primary significatum, even if the concrete accidental term is not the name of the form; on the other, the concrete accidental term can only supposit for the substance. In other words, concrete accidental terms name substances, but indirectly, through the accidental forms from which they take their names, so that they name substances only insofar as they are subject (subiecta) to a form. This fact accounts for both the difference between the general names in the category of substance (such as ‘man’) and concrete accidental terms, and the presence of the relation of identity (or non-identity) in so-called ‘real propositions’ (propositiones in re). General names in the category of substance are concrete terms as well, but the form they primarily signify is really identical to the substances they name. Therefore, in this case, the name of the form is the same as the name of the substance (TsP, ch. de substantia, ed. Conti, p.38; EP, ch. de denominativis, fol. 19va–b). This implies a difference in meaning between abstract and concrete substantial terms (‘humanity’ vs. ‘man’). ‘Humanity’ is not the name of the form considered in its entirety, but only of its essential principle, that is, the intensional content carried by ‘man’, seeing that abstract substantial terms signify substantial forms apart from their own being (esse). In the extramental world, this being coincides with those token-objects (i.e., individual substances) which instantiate the form (QP, q. 4, pp. 271–273).