This work has been carried out as part of the VISTA project [HFF93] [FTS94] [HPR95] and continues a series of doctoral theses on the VISTA framework's architecture [Hal94], on its data level [Fas94] [Rie96], and on its application to CMOS process optimization tasks [Pim93]. CASE tools, system libraries, and the LISP interpreter used in VISTA are treated in [Tup96]. Examples of process simulators developed in the VISTA project can be found in [Str94] and [Puc96]. A graphical editor for defining semiconductor devices in two and three dimensions is described in [Rie96].