GENERIC is a programming language for the description and manipulation of integrated circuits. GENERIC works on the layout level with the designer in complete control of the layout process. To design an integrated circuit, a program is written which hierarchically describes the chip. The dynamic calling structure of the program determines the integrated circuit's hierarchical cell structure. These cells are created by special procedures called generators. Generators are capable of producing completely custom structures-they do not consist of predefined layout. In addition to the specification, GENERIC provides operators for the manipulation of integrated circuit layouts, thus enabling existing geometry to be modified. These modifications can be geometrical, topological or circuit. GENERIC is a very high level language. The language is general purpose-the VLSI aspects of the language are layered on top of the basic language as a run-time library. Since the library itself is written in GENERIC, the language is completely extensible.