The Synthesizer Generator is a system for automating the implementation of language—based editing environments. The editor designer prepares a specification that includes rules defining a language's context—free abstract syn­ tax, context—sensitive relationships, display format, and concrete input syntax. From this specification, the Synthesizer Generator creates a display editor for manipulating objects according to these rules [Reps84]. This volume, The Synthesizer Generator Reference Manual, is intended as the defining document of the system. A companion volume, The Synthesizer Gen­ erator: A System for Constructing Language—Based Editors [Reps88], provides a more tutorial description of the system; it contains numerous examples that illustrate the specification and use of generated editors, as well as chapters that explain important algorithms of the implementation. The Synthesizer Generator is a generalization of our earlier system, the Cor­ nell Program Synthesizer [Teitelbaum81], which was a programming environment for a specific small dialect of PL/I. It featured a display—oriented, syntax­ directed editor, an incremental compiler, an execution supervisor supporting source—level debugging, and a file system containing syntactically typed pro­ gram fragments. Whereas PL/I was built into the Cornell Program Synthesizer, the Synthesizer Generator accepts a formal language definition as input. Although originally conceived as a tool for creating Synthesizer—like environments for arbitrary pro­ gramming languages, the Synthesizer Generator is more broadly useful. Any textual language with a hierarchical phrase structure grammar is a candidate. vi Preface Interactive theorem proving for formal mathematics and logic, for example, has emerged as a particularlysuitable application.