The way we categorize the DEs is based on their behavior when translated into English. This is implicitly done in the work of <cite>Wang et al. (2007)</cite> where they use rules to decide if a certain DE and the words next to it will need to be reordered. Some NPs are translated into a hybrid of these categories, or just don't fit into one of the five categories, for instance, involving an adjectival premodifier and a relative clause.