In this theory, MWEs are classified according to their global POS tags (noun, verb, adverb, adjective), and described in terms of the sequence of the POS tags of the words that constitute the MWE (e.g., "N de N" garde d'enfant [guard of child] ('daycare'), pied de guerre [foot of war] ('at the ready')) (Gross 1986).
mWEs are represented by a flat structure.