Interfaces of the Graphical Kernel System

The GKS standard document defines in a language-independent way a set of functions for performing graphical tasks. However, in an implementation of the system these functions have to be realized as subroutines (or procedures) in a given programming language. Such a language-specific realization, in which the language-independent system nucleus is embedded, is called a language layer. Language layers for FORTRAN and Pascal are available (see examples in Part III, Part IV and Chapter V.4). The functions provided by the language layer can be used by the application programmer, together with operating system functions. In addition, special application-dependent layers can be built on top of the GKS language layer. An example using an application layer for data representation graphics is shown in Figure C7 (page 620), while Figure C8 (page 621) shows a mapping application and Figure C3 (page 619) a CAD application.