Specifies a set of functions for computer graphics programming, the Programmer's Hierarchical Interactive Graphics Systems (PHIGS). PHIGS is a general system for applications that produce computer-generated pictures on line graphics or raster graphics output devices. It supports operator input and interactions by supplying functions for graphical input and hierarchical picture definition. It allows for storage and dynamic modification of pictures. It is identical with and has been reproduced from ISO/IEC 9592-1:1989, Information processing systems - Computer graphics - Programmer's Hierarchical Interactive Graphics System (PHIGS), Part 1: Functional description.