1.1.1.7 CLS

The CLS (C list support) provides a specialized view of PIF data. It is used by applications that need to manipulate PIF geometries, like the graphical interactive PIF data editor (PED [7]). CLS distinguishes between high and low level functions, the latter of which are based on the PIL (PAI interface layer, see Fig. 1.1).

To finish the PIF file format overview one can conclude that PIF was designed in a strict bottom-up fashion. Based on the syntax definition of the file format the library stack (Fig. 1.1 and Fig. 1.4) was developed. The PAL does not have any semantical constraints on the data, only the pure syntax of the file is mapped. There is no definition of the status of a Wafer before and after a simulation run. Instead, the interpretation of the data was delegated directly to the simulation tools. As a consequence several incompatible interpretations were evolving over the time the PAL was integrated with various tools. Due to the bottom-up design semantic constraints on the data (the PIF cookbook) were introduced at a time where tools were already fully integrated with the PAL and could not be changed easily. This brought up the major drawback that, although syntactically compatible, PIF files could not straightforwardly be used to exchange data among simulators. Another drawback of the PIF data level was the comparably huge number of individual functions that emerged during the bottom-up implementation. This results in a confusion of the tool developer who is not familiar with the whole PIF application programming interface (API). Moreover, as is often the case with bottom up approaches, a great percentage of the developed functions are not used in any of the libraries and tools that are existing today.

2003-03-27