This paper intends to extend and elaborate the line of research initiated by Pesetsky and Torrego (2001, 2004) on the role of Tense as a licensing condition over phrasal extraction. In the context of the operation of CP-raising, it re-interprets some instances of T-to-C movement as having not a licensing but a blocking effect over CP-extraction. T-to-C Movement then is analysed as part of an integral operational cycle of gradual saturation comprizing head movement as well as head-agreement. This extended paradigm is analyzed as various degrees of operational completeness, correponding to degrees of "specificity". Within this operational hierarchy of featural specificity resides the mechanism that "opens" or "closes" the syntactic path for phrasal movement to apply. Drawing on data from Belfast English, it is observed that dialectal variation takes place on particular points that lie lower in this hierarchy, in other words at a derivational point of operational "under-specification".
T-to-C movement; head movement; optionality; (under)-specification
