This part of ISO/IEC 9592 specifies a set of functions for computer graphics programming, the Programmer’s Hierarchical Interactive Graphics System (PHIGS). PHIGS is a graphics system for application programs that produce computer generated pictures on output devices. It supports operator input and interactions by supplying basic functions for graphical input and hierarchical picture definition. Picture definitions can be retained centrally where they may be edited by an application. Alternatively, graphical data may be processed without first storing it. To assist in this processing, explicit control over resources used to encapsulate the results of these processing operations is provided. Basic application requirements in the areas of lighting and shading are provided through primitives and functions for controlling the rendering of 3D objects. Utilization of raster images in the generation of PHIGS pictures is provided. Pictures are displayed on output devices which may have associated input devices. Several input devices can be used simultaneously. The application program is allowed to adapt its behaviour to make best use of their capabilities. Graphical output can be constrained to particular views. Views can be specified parametrically and automatic processing of input operations can be used to control viewing. New input devices can be defined from the capabilities available. Functions are specified for archiving picture definitions to file. In addition an interface to the Computer Graphics Metafile (ISO/IEC 8632) is described. This part of ISO/IEC 9592 defines a language independent nucleus of a graphics system for integration into programming language. PHIGS is embedded in a language layer obeying the particular conventions of the language. Such language bindings are specified in ISO/IEC 9593.