This paper describes the analysis component of the language processing system PLAIN from the viewpoint of unification grammers. The principles of Dependency Unification grammar (DUG) are discussed. The computer language DRL (Dependency Representation Language) is introduced in which DUGs can be formulated. A unification-based parsing procedure is part of the formalism. PLAIN is implemented at the universities of Heidelberg, Bonn, Flensburg, Kiel, Zurich and Cambridge U.K.