Describes a file format suitable for the storage and retrieval of PHIGS structure definitions. The file format consists of an ordered set of elements that can be used to describe structures in a way that is compatible between systems of different architectures supporting different programming languages. The archive file is defined in such a way that, in addition to sequential access to the whole archive file, random access to individual structure definitions is well-defined; whether this is available in any system that uses this part of ISO/IEC 9592 depends on the medium, the encoding and the implementation. Covers introduction, references, definitions, concepts and conformance.