the specific referent of [following sumti] defined/specified by the grammar
The grammar in question can itself be specified by metalinguistic tags that apply to the utterance; if not explicitly specified, then a cultural assumption/default is applied. This word is useful for distinguishing between, for example, differentiating between something that the speaker happens to call "PEMDAS" and the order of operations PEMDAS (which, presumably, could be included in the grammar as a special word that influences mekso interpretation); likewise for a font that happens to be called ".mekrot." ("math blackboard bold") and the one that definitely refers to the set of characters used for, among other purposes, set notation.