Overview
ISO/IEC 9592-2:1997 defines the PHIGS archive file format used for storing and transferring PHIGS (Programmer’s Hierarchical Interactive Graphics System) structure and structure-network definitions. The standard specifies the set of archive elements, their organization (syntax) and their intended semantics so that PHIGS structure definitions can be preserved, exchanged and retrieved consistently across different systems, architectures and programming environments. The document separates the functional archive format from any particular encoding (e.g., clear-text or binary), enabling portability and multiple encodings for different application needs.
Key topics and technical requirements
- Archive element classes: Seven classes are defined - delimiter elements, archive file descriptor elements, output primitive elements, attribute elements, modelling transformation elements, miscellaneous elements (labels, execute-structure, name sets, application data, device/system-dependent GSEs), and external elements.
- File structure and grammar: A formal grammar describes top-level constructs (BEGIN ARCHIVE FILE, ARCHIVE FILE VERSION, BEGIN STRUCTURE, STRUCTURE ELEMENT, END STRUCTURE, END ARCHIVE FILE) and how elements compose a valid archive.
- Design principles: Emphasizes completeness, consistency, extensibility, and orthogonality so archive files can fully represent PHIGS structures and be extended without breaking compatibility.
- Encoding independence: Functional specification is independent of encoding. Standard encodings (such as clear-text in ISO/IEC 9592-3) and private encodings are supported; conversion between encodings is anticipated.
- Conformance rules: Two conformance levels - functional conformance (content matches PHIGS functionality, private encoding allowed) and full conformance (functional conformance plus use of a standardized encoding).
- Profiles / versions: Archive file versions map to PHIGS profiles - Version 1 (BASIC), Version 2 (PLUS), Version 3 (FULL).
- Random access: Archive descriptor elements support random access to individual structure definitions where medium, encoding and implementation permit.
- Extensibility for application data: Archive format supports application-dependent data and non-standard elements via GDP/GSE or EXTERNAL element encodings.
Applications and users
- Graphics software developers who implement PHIGS-based systems and need a standardized archive format for structure storage and retrieval.
- System integrators and CAD / visualization tool vendors that exchange scene or model descriptions across different platforms.
- Organizations needing long-term portability of graphical structure definitions, archive/retrieval workflows or migration between implementations.
- Standards bodies and registration authorities managing graphical item identifiers or extensions.
Related standards
- ISO/IEC 9592-1: PHIGS functional description (reference for element semantics)
- ISO/IEC 9592-3: Clear-text encoding of the PHIGS archive file (standard encoding)
- ISO/IEC 8632: MetaFile for storage/transfer of picture description (influences format model)
- Registration Authority: National Institute of Standards and Technology (NIST) - graphical items registry
Keywords: ISO/IEC 9592-2, PHIGS archive file format, PHIGS, computer graphics, archive files, encoding, conformance, clear-text encoding, ISO/IEC 9592-3, structure definitions, portability.