Layer Model of the Graphical Kernel System:

The user communicates along the graphic system by means of his program. The GKS system is embedded in the user program through an application-oriented layer and a language independent layer, thus each layer calls upon the functions of the adjacent lower layer. The following services are available to the user:

• methods for the abstract definition of the peripherals that are needed for a CAD session;
• definition of basic graphic elements, polynomials, text etc.;
• performance of graphic operations such like, rotations, transformation picture segmentation, editing and so on;
• production of a neutral picture file (meta-file) for the system independent storage of data, the exchange of data among different CAD systems and the organization of the output of graphic data;
• definition of a segment file for storing picture segments throughout a CAD session;
• Input and output of graphic information.

Layer Model of the Graphical Kernel System