This part of ISO/IEC 9592 specifies an additional set of functionality of the Programmer s Hierarchical Interactive Graphics System. This additional functionality is intended to satisfy basic application requirements in the areas of lighting and shading and defines additional primitives and functionality for controlling the rendering of 3D objects. It relies on the coexistence of the functions and functionality specified in ISO/IEC 9592-1, and is meant to extend that functionality in the above areas.
It is the intent of this part of ISO/IEC 9592 to be compatible with ISO/IEC 9592-1 and its Amendment 1. That is, in a standard conforming PHIGS PLUS implementation all functions defined in ISO/IEC 9592-1 and not altered by ISO/IEG 9592-4 shall perform as specified in ISO/IEC 9592-1, and all functions defined in ISO/IEC 9592-1 but altered in ISO/IEC 9592-4 shall perform as specified in ISO/IEC 9592-1 and ISO/IEC 9592-4, and, an application functionally conforming to ISO/IEG 9592-1 produces the saure effect running on a standard conforming PHIGS PLUS implementation as it would produce running on a standard conforming PHIGS ISO/1EC 9592-1 implementation, excepting such differentes among implementations as are allowed in ISO/IEC 9592-1. If PHIGS PLUS functions are used, they should only cause the extended effects specified in this part of ISO/IEC 9592. This part of ISO/IEC 9592 defines a language independent extension to a graphics system for integration into a programming language. PHIGS PLUS is embedded in a language layer obeying the particular conventions of the language. Such language bindings are specified for ISO or ISO/IEC languages in ISO/IEC 9593.