In recent works a new type of phrasal structure has been assumed which results by Merging two XPs where neither XP projects: the unlabelled [lled [XP YP]. This structure stands out as an exception with respect to the typical dichotomous repertoire of syntactic structures, namely X°s and XPs. By relying on some core features of Merge in a combinato­rial framework a Matrix is generated which absorbes the stipulative character of this category: moreover, the Matrix reduces some redundancies of UG and predicts the existence of expletives.