Overview
ISO/IEC 9576-1:1995 - Information technology - Open Systems Interconnection - Connectionless Presentation protocol: Protocol specification (Part 1) - specifies the protocol for the connectionless-mode Presentation Layer in the OSI model. This second edition (1995) replaces the 1991 first edition and is published identically as ITU‑T Recommendation X.236. The standard defines the procedures, message structures and encoding rules used when presentation entities exchange data and control information over a connectionless session service.
Key topics and requirements
- Scope and purpose
- Procedures for transfer of data and control between peer presentation entities.
- Structure and encoding of Presentation Protocol Data Units (PPDUs), including the UD PPDU (Unit Data PPDU).
- Interaction definitions between presentation-entity ↔ presentation-service-user and presentation-entity ↔ session-service-provider.
- Protocol model
- Presentation Protocol Machines (PPMs) and their role in connectionless operation.
- Use of Presentation-Service Access Points (PSAPs) and reliance on connectionless session-service primitives.
- Encoding and syntax
- Dependency on ASN.1 abstract/transfer syntax naming and BER/CER/DER encoding rules (ITU‑T X.680–X.690 / ISO/IEC 8824–8825).
- Structure and encoding rules for SS-user data parameter values and values of type User-data.
- Behavior and procedures
- State tables and procedural detail provided (Annex A) to specify element-of-procedure behavior and machine state transitions.
- Mapping of PPDUs onto session-service primitives and rules for PPDU transfer.
- Conformance
- Static and dynamic conformance criteria and the requirement for a Protocol Implementation Conformance Statement (PICS). The standard specifies conformance criteria but does not include test suites.
Applications and who uses this standard
- Implementers of OSI stack components who need a formal specification for the Presentation Layer in connectionless environments.
- Vendors developing network protocol stacks, middleware or interoperable communication software that rely on ASN.1-encoded payloads.
- Systems integrators and standards engineers assuring interoperability between heterogeneous systems that use OSI presentation services.
- Technical writers and test engineers preparing PICS documents and conformance evidence for product certification.
Related standards
- ISO/IEC 7498-1 / ITU‑T X.200 - OSI Basic Reference Model
- ISO/IEC 8822 / ITU‑T X.216 - Presentation Service Definition
- ISO/IEC 8326 / ITU‑T X.215 - Session Service Definition (connectionless)
- ISO/IEC 8824–8825 / ITU‑T X.680–X.690 - ASN.1 and BER/CER/DER encoding rules
- ISO/IEC 9576-2 / ITU‑T X.256 - PICS proforma for this protocol
Keywords: ISO/IEC 9576-1:1995, connectionless presentation protocol, OSI presentation layer, PPDU, ASN.1, BER, PPM, PSAP, connectionless-mode.