Another possible distinction is that between grammatical and lexical monemes. In order to distinguish between them, one should set up the inventories of the monemes which are found in particular contexts, within autonomous phrases, where the respective position of the elements is functionally relevant. Lexical monemes are those which belong to non-limited inventories. Grammatical monemes are those that alternate, in given positions, with a comparatively restricted number of other monemes. The average frequency of grammatical monemes like 'of', 'for', 'with' or Lat. ‘genitive’, ‘dative’, ablative’, is considerably higher than that of lexical monemes such as 'man', 'rich', or 'eat'.
- Martinet (1962), Pag. 50-51