«takes as input a sequence of phrase-structure trees and modifies their labels according to a set of rules. ... Its rule notation is flexible enough to emulate head/argument-finding rules»
P. Koehn, F. Och, and D. Marcu. NAACL '03: Proceedings of the 2003 Conference of the North American Chapter of the Association for Computational Linguistics on Human Language Technology, page 48--54. Morristown, NJ, Association for Computational Linguistics, Association for Computational Linguistics, (2003)