ISO 14721:2025

This document defines the CCSDS and International Organization for Standardization (ISO) Reference Model for an Open Archival Information System (OAIS). An OAIS is an Archive system consisting of hardware, software, information, and policy-based processes and procedures put in place and operated by an organization and its staff.

The organization has accepted the responsibility to preserve information and make it available for a Designated Community. The organization may be part of a larger organization. The system meets a set of mandatory responsibilities that allow an OAIS Archive to be distinguished from other uses of the term ‘archive’. The set of mandatory responsibilities an OAIS Archive must perform are defined in 3.2. The term ‘Open’ in OAIS is used to imply that this Recommended Practice, as well as future related Recommended Practices and standards, are developed in open forums, and it does not imply that access to the Archive is unrestricted.

The information being maintained has been deemed to need Long Term Preservation, even if the OAIS itself is not permanent. Long Term is long enough to be concerned with the impacts of changing technologies, as well as support for new media and data formats, or with a changing Knowledge Base of the Designated Community or changes within the Designated Community or its definition. Long Term may extend indefinitely.

In this Reference Model there is a particular focus on digital information, both as the primary forms of information held and as supporting information for both digitally and physically preserved materials. Therefore, the model accommodates information that is inherently non-digital (e.g., a physical sample), but the modelling and preservation of such information is not addressed in detail.

This Reference Model:

• provides a framework for the understanding and increased awareness of archival concepts needed for Long Term digital information preservation and access;
• provides the concepts needed by non-archival organizations to be effective participants in the preservation process;
• provides a framework, including terminology and concepts, for describing and comparing architectures and operations of existing and future Archives;
• provides a framework for describing and comparing different Long Term Preservation strategies and techniques;
• provides a basis for comparing the data models of digital information preserved by Archives and for discussing how the data models and the underlying information may change over time;
• provides a framework that may be expanded by other efforts to cover Long Term Preservation of information that is NOT in digital form (e.g., physical media and physical samples);
• expands consensus on the elements and processes for Long Term digital information preservation and access, and promotes a larger market which vendors can support;
• guides the identification and production of OAIS-related standards.

The reference model addresses a full range of archival information preservation functions including ingest, archival storage, data management, access, and dissemination. It also addresses the migration of digital information to new media and forms, the information models used to represent the information, the role of software in information preservation, and the exchange of digital information among Archives. It identifies both internal and external interfaces to the Archive functions, and it identifies a number of high-level services at these interfaces.

It provides various illustrative examples and some ‘best practice’ recommendations. It defines a minimal set of responsibilities for an Archive to be called an OAIS, and it also defines a maximal Archive to provide a broad set of useful terms and concepts.