It is useful to point out the differences that may exist between different grammatical typologies. The classical grammatical taxonomy is essentially aimed at teaching and comprehension. It therefore has a pedagogical purpose. On the other hand, the taxonomy that is useful for rule-based machine translation has a different purpose: it aims essentially at allowing disambiguation, both grammatically and semantically, because ambiguity is a fundamental and very common problem in this particular context. Such a typology essentially focuses on the location of word types, on the structures encountered in the sentence. This explains why typologies can be different, as they have different goals and purposes.