The difference between functionals and modifiers, i.e the two types of grammatical monemes, should not be expressed in semantic terms, although modifiers are likely to be semantically richer than functionals. It should be based upon the part each type plays in the sentence.
- Martinet (1962), Pag. 96

Whether this or that functional may or may not be used is partially determined by the communicative needs at that point of the utterance: after 'he is distributing tickets', I may or may not specify 'to' whom. But it also depends on which predicative moneme I choose, whether I may or may not use a 'to'-complement. It is what is referred to when we say that a given verb governs this or that case . This amounts to saying that, to a large extent, the choice of a functional is predetermined by that of the verb of the clause. On the contrary, the choice of the modifier is free, i.e. the speaker is determined to use 'a' or 'the', the plural or the singular, at a certain point by direct reference to what the experience really is that he wants to communicate […] In spite of such fundamental differences, functionals and modifiers have so far generally been confused, and it is easy to understand why linguists who, in their overwhelming majority, had been taught Latin grammar first, were tempted, at best,to consider them two aspects of the same linguistic reality. In Latin as in all Indo- European languages that have preserved the old declensions, the expression of the case and that of number are hopelessly mixed under the form of case-endings that resist any formal analysis into successive segments. In other words, amalgams of a functional and one modifier, or more than one, are practically rule there, and must have been felt by generations of linguists to be a normal feature of any self-respecting language structure.
- Martinet (1962), Pag. 52-53