Discourse-linked interrogative phrase
A discourse-linked (or d-linked) interrogative phrase is an interrogative phrase like which man that implies the existence of a context set of familiar entities of the type denoted by the nominal (e.g., a set of already familiar men) (Pesetsky 1987, Enç 1991). They contrast with non-discourse linked interrogative pronouns such as who, which carry no necessary implication about familiar discourse entities.
The distinction between discourse-linked and non-discourse-linked interrogative phrases has been shown to be relevant for syntax in some cases. As Pesetsky (1987) noted, discourse-linked phrases can violate superiority:
(2) a. Mary asked [who[e read what]]? b. *Mary asked [what[who read e]]? (3) a. Mary asked which man [e read which book]? b. Mary asked which book [which man read e]?