ISO 14721:2025

Space Data System Practices - Reference model for an open archival information system (OAIS)

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 REF _Ref511638039 \r \h 3.2 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000E0000005F005200650066003500310031003600330038003000330039000000 . 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.

Pratiques des systèmes de données spatiales — Modèle de référence pour un système ouvert d'archivage d'information (SOAI)

Prakse sistemov za trajno ohranjanje podatkov - Referenčni model za odprti arhivski informacijski sistem (OAIS)

General Information

• Status: Published
• Publication Date: 09-Mar-2025
• ICS: 49.140 - Space systems and operations
• Technical Committee: ISO/TC 20/SC 13 - Space data and information transfer systems
• Drafting Committee: ISO/TC 20/SC 13 - Space data and information transfer systems
• Current Stage: 6060 - International Standard published
• Start Date: 10-Mar-2025
• Due Date: 14-Jul-2025
• Completion Date: 07-Mar-2025
• Ref Project: SIST ISO 14721:2025 - Space Data System Practices - Reference model for an open archival information system (OAIS)

Relations

• Revises: ISO 14721:2012 - Space data and information transfer systems - Open archival information system (OAIS) - Reference model
• Effective Date: 15-Jul-2023

Overview

ISO 14721:2025 - ISO 14721:2025 (OAIS) defines the CCSDS/ISO Reference Model for an Open Archival Information System (OAIS). This internationally adopted standard establishes the conceptual framework, terminology and mandatory responsibilities for organizations that accept long‑term preservation and access of digital information. The OAIS model covers hardware, software, information and policy‑based processes operated by an archive to preserve information for a defined Designated Community. Keywords: OAIS, ISO 14721:2025, digital preservation, long term preservation, open archival information system, CCSDS.

Key topics and technical requirements

• Mandatory responsibilities (Clause 3.2): The standard defines a minimal set of responsibilities an archive must perform to be called an OAIS (see clause 3.2 for the authoritative list).
• Functional model: Core archival functions are specified, including Ingest, Archival Storage, Data Management, Access, Preservation Planning and Administration.
• Information model and packages: Concepts such as Information Object, Content Information, Preservation Description Information (PDI), and Information Packages (e.g., AIP) are defined to describe how digital data and metadata are packaged for preservation.
• Preservation techniques: Guidance on migration, adding Representation Information, and other preservation strategies to respond to changing technologies and formats.
• Interoperability and interfaces: Identification of internal and external interfaces, high‑level services, and levels of interaction among OAIS archives (including federation and exchange scenarios).
• Preservation objectives and monitoring: Introduction of Preservation Objectives and a Preservation Watch function to support testable understandability and ongoing monitoring of technological and knowledge‑base changes.
• Documentation and examples: Illustrative diagrams, best‑practice recommendations, and informative annexes on related efforts, software roles, UML guidance and security considerations.

Practical applications and users

Who uses ISO 14721:2025:

• National and institutional archives, space agencies, research data centers and libraries implementing digital preservation programs.
• IT architects and system designers defining archival architectures and storage strategies.
• Data managers and curators creating ingest, access and preservation workflows.
• Vendors and service providers developing OAIS‑aware archival software and storage solutions. Practical uses include defining preservation policies, designing AIP/AIC data flows, establishing interoperability agreements, and evaluating archive conformance against OAIS responsibilities.

Related standards and context

• Prepared by CCSDS (as CCSDS 650.0-M-3) and adopted by ISO/TC 20/SC 13.
• Cross‑references and consistency with other CCSDS/ISO documents (for example Producer‑Archive Interface Specification) are noted in the standard.

ISO 14721:2025 is the authoritative reference for organizations aiming to implement robust, interoperable and standards‑based digital preservation systems.

Standards Content (Sample)

SLOVENSKI STANDARD
01-december-2025
Nadomešča:
SIST ISO 14721:2013
Prakse sistemov za trajno ohranjanje podatkov - Referenčni model za odprti
arhivski informacijski sistem (OAIS)
Space Data System Practices - Reference model for an open archival information
system (OAIS)
Pratiques des systèmes de données spatiales - Modèle de référence pour un système
ouvert d'archivage d'information (SOAI)
Ta slovenski standard je istoveten z: ISO 14721:2025
ICS:
35.240.99 Uporabniške rešitve IT na IT applications in other fields
drugih področjih
49.140 Vesoljski sistemi in operacije Space systems and
operations
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

International
Standard
ISO 14721
Third edition
Space Data System Practices —
2025-03
Reference model for an open
archival information system (OAIS)
Pratiques des systèmes de données spatiales — Modèle de
référence pour un système ouvert d'archivage d'information (SOAI)
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
CCSDS RECOMMENDED PRACTICE FOR AN OAIS REFERENCE MODEL
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national
standards bodies (ISO member bodies). The work of preparing International Standards is
normally carried out through ISO technical committees. Each member body interested in a
subject for which a technical committee has been established has the right to be represented on
that committee. International organizations, governmental and non-governmental, in liaison
with ISO, also take part in the work. ISO collaborates closely with the International
Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance
are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria
needed for the different types of ISO document should be noted (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the
use of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of
any claimed patent rights in respect thereof. As of the date of publication of this document, ISO
had not received notice of (a) patent(s) which may be required to implement this document.
However, implementers are cautioned that this may not represent the latest information, which
may be obtained from the patent database available at www.iso.org/patents. ISO shall not be
held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and
does not constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO’s adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by the Consultative Committee for Space Data Systems (CCSDS)
(as CCSDS 650.0-M-3, December 2024) and drafted in accordance with its editorial rules. It was
assigned to Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee SC 13,
Space data and information transfer systems and adopted under the “fast-track procedure”.
This third edition cancels and replaces the second edition (ISO 14721:2012), which has been
technically revised.
The main changes are as follows:
— Changes from the current issue are too numerous to permit meaningful markup.
— This issue has additions to, and clarifications of, concepts and terminology, for example:
— The relationship between Preservation Description Information (PDI) and
Content Data Object has been clarified, emphasizing that, as has been stated
since the original version of OAIS, any Information Object may serve as Content
Information.
CCSDS 650.0-M-3 Page iii December 2024
CCSDS RECOMMENDED PRACTICE FOR AN OAIS REFERENCE MODEL
— The concept of Preservation Objectives has been introduced to allow
“Independently Understandable” to be more consistently testable.
— Consistency with the Producer-Archive Interface Specification (PAIS) (CCSDS
651.1-B-1) has been improved.
— Diagram conventions have been clarified.
— Some definitions in the Glossary have been clarified.
— Consistency between the diagrams of the Functional Entities and supporting
text has been improved.
— A Preservation Watch function has been added to the Preservation Planning
Functional Entity.
— The definition of the Information Package has been updated for consistency.
— Additional preservation techniques have been described explicitly in addition to
Migration.
— Additional types of Archive interaction have been added, including primary-
supporting Archives.
— Annex A is marked as Informative. It had previously erroneously been marked
as Normative.
— Annex B from the previous issue described the relationship of OAIS to other
standards; but its contents were continually out of date as those other
standards develop along different directions and timelines as compared to OAIS
development. Also, subsection 1.5 from the previous issue, which provided a
roadmap to related Standards which could be developed was removed since a
number of those standards are now available. Both have been replaced by
pointers in annex B to informative documents on the CCSDS web site which can
be updated more rapidly.
Any feedback or questions on this document should be directed to the user’s national standards
body. A complete listing of these bodies can be found at www.iso.org/members.html.

CCSDS 650.0-M-3 Page iv December 2024
CCSDS RECOMMENDED PRACTICE FOR AN OAIS REFERENCE MODEL
CONTENTS
Section Page
1 INTRODUCTION . 1-1

1.1 PURPOSE AND SCOPE . 1-1
1.2 APPLICABILITY . 1-2
1.3 RATIONALE . 1-3
1.4 CONFORMANCE . 1-3
1.5 DOCUMENT STRUCTURE . 1-4
1.6 DEFINITIONS . 1-7

2 OAIS CONCEPTS . 2-1

2.1 GENERAL . 2-1
2.2 OAIS ENVIRONMENT . 2-2
2.3 OAIS INFORMATION . 2-3
2.4 PRESERVATION OBJECTIVES . 2-8
2.5 SUPPLEMENTARY INFORMATION HELD BY THE ARCHIVE . 2-9
2.6 OAIS HIGH-LEVEL EXTERNAL INTERACTIONS . 2-10

3 OAIS RESPONSIBILITIES. 3-1

3.1 OVERVIEW . 3-1
3.2 MANDATORY RESPONSIBILITIES . 3-1
3.3 EXAMPLE MECHANISMS FOR DISCHARGING RESPONSIBILITIES . 3-2

4 DETAILED MODELS . 4-1

4.1 OVERVIEW . 4-1
4.2 FUNCTIONAL MODEL . 4-1
4.3 INFORMATION MODEL. 4-22
4.4 INFORMATION PACKAGE TRANSFORMATIONS . 4-55

5 PRESERVATION PERSPECTIVES . 5-1

5.1 OVERVIEW . 5-1
5.2 DIGITAL MIGRATION . 5-2
5.3 ADDING REPRESENTATION INFORMATION . 5-11
5.4 HANDING OVER TO ANOTHER OAIS . 5-16

6 ARCHIVE INTEROPERABILITY . 6-1

6.1 GENERAL . 6-1
6.2 LEVELS OF INTERACTION BETWEEN OAIS ARCHIVES . 6-2
CCSDS 650.0-M-3 Page v December 2024
CCSDS RECOMMENDED PRACTICE FOR AN OAIS REFERENCE MODEL
CONTENTS (continued)
Section Page
ANNEX A COMPOSITE FUNCTIONAL VIEW (INFORMATIVE) . A-1
ANNEX B RELATIONSHIP WITH OTHER STANDARDS OR
EFFORTS (INFORMATIVE) . B-1
ANNEX C BRIEF GUIDE TO THE UNIFIED MODELING
LANGUAGE (UML) (INFORMATIVE) . C-1
ANNEX D INFORMATIVE REFERENCES (INFORMATIVE). D-1
ANNEX E A MODEL FOR SOFTWARE USE IN REPRESENTATION
INFORMATION (INFORMATIVE) . E-1
ANNEX F SECURITY CONSIDERATIONS (INFORMATIVE) . F-1
Figure
1-1 Examples of Diagram Conventions . 1-6
2-1 Environment Model of an OAIS . 2-2
2-2 Obtaining Information from Data . 2-4
2-3 Information Package Concepts and Relationships . 2-6
2-4 OAIS Archive External Data . 2-10
4-1 OAIS Functional Entities . 4-1
4-2 Functions of the Ingest Functional Entity . 4-6
4-3 Functions of the Archival Storage Functional Entity . 4-8
4-4 Functions of the Data Management Functional Entity . 4-10
4-5 Functions of the Administration Functional Entity . 4-12
4-6 Functions of the Preservation Planning Functional Entity . 4-15
4-7 Functions of the Access Functional Entity . 4-18
4-8 OAIS Data Flow Diagram . 4-20
4-9 Administration Context Diagram . 4-21
4-10 Information Object . 4-23
4-11 Representation Information Object . 4-26
4-12 Partial General RIN . 4-27
4-13 Example of a Simplified RIN for a FITS File . 4-28
4-14 Information Object Taxonomy . 4-31
4-15 Information Package Contents and Its Associated Package
Description and Packaging Information. 4-39
4-16 Example of an Information Object Made Up of Content
Information and PDI . 4-39
4-17 Information Package Taxonomy . 4-40
4-18 Archival Information Package (AIP) and Its Associated Package
Description and Packaging Information. 4-42
4-19 Preservation Description Information . 4-43
4-20 Package Description and Its Associated AIP . 4-44
CCSDS 650.0-M-3 Page vi December 2024
CCSDS RECOMMENDED PRACTICE FOR AN OAIS REFERENCE MODEL
CONTENTS (continued)
Figure Page
4-21 Archival Information Package (Detailed View) and Its Associated
Package Description and Packaging Information . 4-45
4-22 Specialization of the AIP . 4-46
4-23 Specialization of the Package Description . 4-47
4-24 Archival Information Unit (AIU) and Its Associated Unit
Description and Packaging Information. 4-48
4-25 Unit Description and Its Associated Archival Information Unit . 4-48
4-26 Archival Information Collections and Its Associated Collection
Description and Packaging Information Logical View . 4-50
4-27 Collection Description and Its Associated Archival Information Collection . 4-52
4-28 Data Management Information . 4-55
4-29 High-Level Data Flows in an OAIS . 4-56
5-1 Conceptual View of Relationships among Names and AIP Components . 5-4
6-1 Cooperating Archives with Mutual Exchange Agreement . 6-4
6-2 Cooperating Archives with Standard Ingest and Access Methods . 6-5
6-3 An OAIS Federation Employing a Common Catalog . 6-6
6-4 Archives with Shared Storage . 6-10
6-5 Example of a Distributed OAIS Archive for Archival Storage . 6-12
6-6 Another Example of a Distributed OAIS Archive for Archival Storage . 6-14
A-1 Composite of Functional Entities . A-2
C-1 Key to UML Relationships . C-1
E-1 Layered Information Model . E-1
Table
4-1 Examples of PDI . 4-36
5-1 CDO Software Roles and Preservation Possible Actions . 5-14

CCSDS 650.0-M-3 Page vii December 2024
CCSDS RECOMMENDED PRACTICE FOR AN OAIS REFERENCE MODEL
1 INTRODUCTION
1.1 PURPOSE AND SCOPE
The purpose of this document is to define 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.
CCSDS 650.0-M-3 Page 1-1 December 2024
CCSDS RECOMMENDED PRACTICE FOR AN OAIS REFERENCE MODEL
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.
1.2 APPLICABILITY
The OAIS model in this document may be applicable to any Archive. It is specifically
applicable to organizations, which may themselves be part of larger organizations, with the
responsibility of making information available for the Long Term (as defined in 1.6.2). This
includes organizations with other responsibilities, such as receiving, processing and
distribution in response to programmatic needs.
Organizations may require their information, from the start, to be re-processable to enable the
results created by others to be reproduced, interoperable with other information, and re-used
in new ways. Such organizations will find this document relevant because of the requirement
that, to be preserved, the information must be understandable and usable.
This model is also of interest to those organizations and individuals who create information
that may need Long Term Preservation and those that may need to acquire information from
such Archives.
The model, including the functional and information modelling concepts, is relevant to the
comparison and design of facilities which hold information, on a temporary basis, for two
reasons:
– When taking into consideration the rapid pace of technology changes or possible
changes in a Designated Community, there is the likelihood that facilities, thought to
be holding information on a temporary basis, will in fact find that some or much of
their information holdings will need Long Term Preservation attention.
– Although some facilities holding information may themselves be temporary, some or
all of their information may need to be preserved indefinitely. Such facilities need to
be active participants in the Long Term Preservation effort.
Standards developers are expected to use this model in conjunction with related standards
and community documents as a basis for further standardization in this area. Many related
standards are possible and some have already been developed. Annex B includes links to
websites containing references to a selection of related standards.
This reference model does not specify a design or an implementation. Actual
implementations may group or break out functionality differently.
CCSDS 650.0-M-3 Page 1-2 December 2024
CCSDS RECOMMENDED PRACTICE FOR AN OAIS REFERENCE MODEL
1.3 RATIONALE
A tremendous growth in computational power, and in networking bandwidth and
connectivity, has resulted in an explosion in the number of organizations making digital
information available. Transactions among all types of organizations are being conducted
using digital forms that are taking the place of more traditional media such as paper.
Preserving information in digital forms is much more difficult than preserving information in
forms such as paper and film. This is not only a problem for traditional archives, but also for
many organizations that have never thought of themselves as performing an archival
function. Along with the many advantages in terms of, for example, searchability and
replication, the spread of digital technology in every field brings certain disadvantages. The
rapid obsolescence of digital technologies creates considerable technical dangers, particularly
a much greater risk than in the past of losing the possibility of restoring, rendering or
interpreting the information. Ways of avoiding or reducing these dangers will be detailed
throughout this Recommended Practice. Nevertheless, it would be unwise to consider the
problem from a solely technical standpoint. There are also organizational, legal, industrial,
scientific and cultural issues to be considered. To ignore the problems raised by preserving
information in digital forms would lead inevitably to the loss of this information. In addition,
information is more and more easily altered or faked. Ways to be more sure of the
authenticity of information, by knowing its provenance and being sure that it has not been
altered, will help to counter these threats
It is expected that this reference model, by establishing minimum requirements for an OAIS
Archive along with a set of archival concepts, will provide a common framework from which
to view archival challenges, particularly as they relate to digital information. This should
enable more organizations to understand the issues and take the proper steps to ensure Long
Term information preservation. It should also provide a basis for more standardization and,
therefore, a larger market that vendors can support in meeting archival requirements.
1.4 CONFORMANCE
A conforming OAIS Archive implementation shall support, and be able to map to the
components of, the model of information described in 2.3 and 4.3, which provides more
formal definitions of the model using UML. The OAIS Reference Model does not define or
require any particular method of implementation of these concepts.
A conforming OAIS Archive shall fulfil the responsibilities listed in 3.2. Subsection 3.3
provides examples of the mechanisms that may be used to discharge the responsibilities
identified in 3.2. These mechanisms are not required for conformance.
A conformant OAIS Archive may provide additional services that are beyond those
required of an OAIS.
This reference model does not specify a design or an implementation. Actual
implementations may group or break out functionality differently.
CCSDS 650.0-M-3 Page 1-3 December 2024
CCSDS RECOMMENDED PRACTICE FOR AN OAIS REFERENCE MODEL
It is assumed that implementers will use this reference model as a guide while developing a
specific implementation to provide identified services and content. This document does not
assume or endorse any specific computing platform, system environment, system design
paradigm, system development methodology, database management system, database design
paradigm, data definition language, command language, system interface, user interface,
technology, or media required for implementation.
The OAIS Reference Model is designed as a conceptual framework in which to discuss and
compare Archives. As such, it attempts to address all the major activities of an information-
preserving Archive in order to define a consistent and useful set of terms and concepts. A
standard or other document that claims to be conformant to the OAIS Reference Model shall
use the terms and concepts defined in the OAIS Reference Model in the same manner.
Subsection 1.6.2 defines OAIS terminology and is normative.
To summarize, to be conformant with OAIS, an Archive must support the basic terminology
specified in section 1.6.2, must be able to map its practices to the OAIS Information Model,
which is defined at very high level in 2.3 and in more detail in 4.3, and must also fulfill the
Mandatory Responsibilities specified in 3.2.
1.5 DOCUMENT STRUCTURE
1.5.1 HOW TO READ THIS DOCUMENT
All readers should read the Purpose and Scope (1.1), Applicability (1.2), and Conformance (1.4)
subsections to obtain a view on the objectives and applicability of the document.
Those who want just an overview of the major concepts should also read OAIS Concepts
(section 2) and OAIS Responsibilities (section 3).
Those who will implement OAIS Archives or administer them should read the entire
document.
1.5.2 ORGANIZATION BY SECTION
Section 1 provides purpose, scope, applicability, and definitions sections typical of many
standards. It also provides rationale for the effort and conformance requirements.
Section 2 provides a high-level overview of the major concepts involved in an OAIS
Archive. It provides a view of the environment of an OAIS Archive and the roles played by
those who interact with it. It discusses what is meant by ‘information’ and what is necessary
to preserve it for the Long Term. It contains key information concepts relevant to OAIS-
conforming implementations.
CCSDS 650.0-M-3 Page 1-4 December 2024
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Section 3 describes the responsibilities required of an OAIS. Subsection 3.2 defines
mandatory responsibilities an OAIS Archive must discharge in preserving its information,
and 3.3 provides clarifying material of the types of activities that may be needed in many
Archives to discharge these responsibilities.
Section 4 provides model views needed for a detailed understanding of an OAIS Archive. It
breaks down the OAIS into a number of informative abstract functional entities and it
describes some abstract high-level services provided at the interfaces of these entities. It also
provides normative information models using Unified Modeling Language (UML) class
diagrams.
Section 5 provides some perspectives on the issues of information preservation. It also
provides some perspectives on the issues of preserving access services to digital information
using software porting, wrapping, and emulation of hardware.
Section 6 is an introduction to the various alternatives for Archive-to-Archive associations to
provide increased or more cost-effective services.
The annexes B-F are not part of the Recommended Practice and are provided for the
convenience of the reader:
– annex A provides a composite diagram of the detailed functional entities described in 4.2;
– annex B contains pointers to external documents which relates parts of this reference
model to other standards work and provides a guide for development of related
standards;
– annex C provides a brief tutorial on the Unified Modeling Language class diagrams
(UML);
– annex D provides a list of informative references;
– annex E provides a layered model of information;
– annex F provides an overview of security considerations.
1.5.3 DIAGRAM CONVENTIONS
Except where indicated otherwise, diagrams show entities such as people or organizations as
round cornered long rectangles, functions as rectangles with round corners and functional
entities as rectangles with cut corners, with information between them as arrows, and special
information objects as ellipses as illustrated in figure 1-1.
CCSDS 650.0-M-3 Page 1-5 December 2024
CCSDS RECOMMENDED PRACTICE FOR AN OAIS REFERENCE MODEL
function
E
N
T
I Functional
T
Entity
I
E
Special
S
Information
Figure 1-1: Examples of Diagram Conventions
To serve as visual clues, consistent colors have been adopted for each Functional Entity and its
component Functions; however, the diagrams do not depend upon these colors to be usable.
1.5.4 TYPOGRAPHICAL CONVENTIONS
There are many terms which are used in this reference model and which need to have well-
defined meanings. These terms are defined in 1.6.2. When first used in the text, they are
shown in bold and are capitalized. Subsequent use employs capitalization only. Because of
their extensive use in this document, the defined terms ‘data’ and ‘information’ will not
always be capitalized unless they are part of another defined term. The defined term ‘archive’
will not be capitalized unless it is used as the equivalent of an ‘OAIS Archive’.
Many diagrams are included throughout this reference model, primarily in sections 4 and 6.
In text discussing the diagrams, block names are capitalized and flows are italicized.
1.5.5 NOMENCLATURE
1.5.5.1 Normative Text
The following conventions apply for the normative specifications in this Recommended
Practice:
a) the words ‘shall’ and ‘must’ imply a binding and verifiable specification;
b) the word ‘should’ implies an optional, but desirable, specification;
c) the word ‘may’ implies an optional specification;
d) the words ‘is’, ‘are’, and ‘will’ imply statements of fact.
NOTE – These conventions do not imply constraints on diction in non-normative text.
CCSDS 650.0-M-3 Page 1-6 December 2024
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1.6 DEFINITIONS
1.6.1 ACRONYMS AND ABBREVIATIONS
AIC Archival Information Collection
AIP Archival Information Package
AIU Archival Information Unit
API Application Programming Interface
ASCII American Standard Code for Information Interchange
CCSDS Consultative Committee for Space Data Systems
CD-ROM Compact Disk-Read Only Memory
CDO Content Data Object
CPU Central Processing Unit
CRC Cyclic Redundancy Check
CSV Comma Separated Value
DBMS Data Base Management System
DIP Dissemination Information Package
DRM Digital Rights Management
FITS Flexible Image Transport System
FTP File Transfer Protocol
HFMS Hierarchical File Management System
HTTP HyperText Transfer Protocol.
ID Identifier
IEEE Institute of Electrical and Electronics Engineers
IETF Internet Engineering Task Force
ISBN International Standard Book Number
ISO International Organization for Standardization
MPEG Moving Picture Experts Group
OAIS Open Archival Information System
PDF Portable Document Format
CCSDS 650.0-M-3 Page 1-7 December 2024
CCSDS RECOMMENDED PRACTICE FOR AN OAIS REFERENCE MODEL
PDI Preservation Description Information
QA Quality Assurance
RFC Request For Comment
SIP Submission Information Package
TCP/IP Transmission Control Protocol/Internet Protocol
UML Unified Modeling Language
USB Universal Serial Bus
VHS Video Home System
WWW World Wide Web
XFDU XML Formatted Data Unit
XML eXtensible Markup Language
1.6.2 TERMINOLOGY
This subsection is normative.
There are many terms which are used in this reference model and which need to have well-
defined meanings. These terms are defined in this subsection. When first used in the text,
they are shown in bold and are capitalized. Subsequent use employs capitalization only.
In other CCSDS documents the terms such as ‘service’ and ‘object’ have different definitions
from those used here. Where confusion may arise then the terms from this document may be
prefixed with ‘OAIS’.
As this reference model is applicable to all disciplines and organizations that do, or expect to,
preserve and provide information in digital form, these terms cannot match all of those familiar
to any particular discipline (e.g., traditional archives, digital libraries, science data centers).
Rather, the approach taken is to use terms that are not already overloaded with meaning so as to
reduce conveying unintended meanings. Therefore, it is expected that all disciplines and
organizations will find that they need to map some of their more familiar terms to those of the
OAIS Reference Model. This should not be difficult and is viewed as a contribution, rather
than a deterrent, to the success of the reference model. For example, archival science focuses
on preservation of the ‘record’. This term is not used in the OAIS Reference Model, but one
mapping might approximately equate it with ‘Content Information within an Archival
Information Package’ (see definitions below, as well as 2.3 and 4.3 for context).
Access Aid: A software program or document that allows Consumers to locate, analyze,
order or retrieve information from an OAIS.
CCSDS 650.0-M-3 Page 1-8 December 2024
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Access Collection: A collection of AIPs that is defined by a Collection Description but for
which there is no Packaging Information for the collection in Archival Storage.
Access Functional Entity: The OAIS functional entity that provides the services and
functions that support Consumers in determining the existence, description, location and
availability of information stored in the OAIS, and allowing Consumers to request and
receive information products.
Access Rights Information: The information that identifies the access restrictions pertaining
to the Content Data Object, including the legal framework, licensing terms, and access
control. It contains the access and distribution conditions stated within the Submission
Agreement, related to both preservation (by the OAIS) and final usage (by the Consumer). It
also includes the specifications for the application of rights enforcement measures.
Access Software: A type of software that presents part of or all of the information content of
an Information Object in forms understandable to or usable by humans or their proxy
systems.
Ad-hoc Order: A request that is generated by a Consumer for information the OAIS has
indicated is currently available.
Administration Functional Entity: The OAIS functional entity that provides the services
and functions needed to control the operation of the other OAIS functional entities on a day-
to-day basis.
AIP Edition: An AIP whose Content Information or Preservation Description Information
has been subject to an upgrade or improvement which was not required for preservation. An
AIP edition is not considered to be the result of a Migration.
AIP Version: An AIP resulting from changing the Content Information or Preservation
Description Information of a source AIP, in order to preserve the information. An AIP
Version is considered to be the result of a Migration.
Archival Information Collection (AIC): An Archival Information Package whose Content
Information is an aggregation of other Archival Information Packages.; its PDI must include
a description of the collection criteria and process.
NOTE – At a minimum all OAISes can be viewed as having at least one AIC which
contains all the AIPs held by the OAIS.
Archival Information Package (AIP): An Information Package, consisting of the Content
Information and the associated Preservation Description Information (PDI), which is
preserved within an OAIS.
Archival Information Unit (AIU): An Archival Information Package where the Content
Information does not include any other Archival Information Packages. An AIU can consist
of multiple digital objects, for example, multiple files.
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Archival Storage Functional Entity: The OAIS functional entity that provides the services
and functions used for the storage and retrieval of Archival Information Packages.
Archive: An organization that intends to preserve information for access and use by a
Designated Community.
Associated Description: The information describing the content of an Information Package
from the point of view of a particular Access Aid.
Authenticity: The degree to which a person (or system) regards an object as what it is
purported to be. Authenticity is judged on the basis of evidence.
Collection Description: A type of Package Description that is specialized to provide
information about an Archival Information Collection (or an Access Collection) for use by
Access Aids.
Common Services: The supporting services such as inter-process communication, name
services, temporary storage allocation, exception handling, security, and directory services
necessary to support the OAIS.
Consumer: The role played by those persons, or client systems, who interact with OAIS
services to find preserved information of interest and to access that information in whatever
level of detail is allowed. In addition to the normally expected entities outside the OAIS, this
can also include other OAISes, as well as internal OAIS persons or systems.
Content Data Object: The Data Object, that together with associated Representation
Information, comprises the Content Information.
Content Information: A set of information that is the original target of preservation. It is an
Information Object composed of its Content Data Object and its Representation Information.
Context Information: The information that documents the relationships of the Content Data
Object to its environment. This includes why the Content Data Object was created and how it
relates to other Content Data Objects.
Co-operating Archives: Those Archives that have Designated Communities with related
interests. They may order and ingest data from each other. At a minimum, Co-operating
Archives must agree to support at least one common Submission Information Package (SIP)
and Dissemination Information Package (DIP) for inter-Archive requests.
Data: A reinterpretable representation of information in a formalized manner suitable for
communication, interpretation, or processing.
NOTE – Examples of data include a sequence of bits, a table of numbers, the characters on a
page, the recording of sounds made by a person speaking, or a moon rock specimen.
Data Dictionary: A formal repository of terms used to describe data.
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Data Dissemination Session: A delivery of media or a single telecommunications session
that provides Data to a Consumer. The Data Dissemination Session format/contents is based
on a data transfer specification negotiated between the OAIS and the Consumer in the Order
Agreement. This specification identifies the logical constructs used by the OAIS and how
they are represented on each media delivery or in the telecommunication session.
Data Management Data: The data created and stored in Data Management persistent
storage that refer to operation of an Archive.
NOTE – Examples of Data Management Data are accounting data for Consumer billing
and authorization, policy data, Event Based Order (subscription) data for
repeating requests, preservation process history data, and statistical data for
generating reports to Archive management.
Data Management Functional Entity: The OAIS functional entity that provides the
services and functions for populating, maintaining, and accessing both Descriptive
Information which identifies and documents Archive holdings and administrative data used
to manage the Archive.
D
...

International
Standard
ISO 14721
Third edition
Space Data System Practices —
2025-03
Reference model for an open
archival information system (OAIS)
Pratiques des systèmes de données spatiales — Modèle de
référence pour un système ouvert d'archivage d'information (SOAI)
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
CCSDS RECOMMENDED PRACTICE FOR AN OAIS REFERENCE MODEL
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national
standards bodies (ISO member bodies). The work of preparing International Standards is
normally carried out through ISO technical committees. Each member body interested in a
subject for which a technical committee has been established has the right to be represented on
that committee. International organizations, governmental and non-governmental, in liaison
with ISO, also take part in the work. ISO collaborates closely with the International
Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance
are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria
needed for the different types of ISO document should be noted (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the
use of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of
any claimed patent rights in respect thereof. As of the date of publication of this document, ISO
had not received notice of (a) patent(s) which may be required to implement this document.
However, implementers are cautioned that this may not represent the latest information, which
may be obtained from the patent database available at www.iso.org/patents. ISO shall not be
held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and
does not constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO’s adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by the Consultative Committee for Space Data Systems (CCSDS)
(as CCSDS 650.0-M-3, December 2024) and drafted in accordance with its editorial rules. It was
assigned to Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee SC 13,
Space data and information transfer systems and adopted under the “fast-track procedure”.
This third edition cancels and replaces the second edition (ISO 14721:2012), which has been
technically revised.
The main changes are as follows:
— Changes from the current issue are too numerous to permit meaningful markup.
— This issue has additions to, and clarifications of, concepts and terminology, for example:
— The relationship between Preservation Description Information (PDI) and
Content Data Object has been clarified, emphasizing that, as has been stated
since the original version of OAIS, any Information Object may serve as Content
Information.
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— The concept of Preservation Objectives has been introduced to allow
“Independently Understandable” to be more consistently testable.
— Consistency with the Producer-Archive Interface Specification (PAIS) (CCSDS
651.1-B-1) has been improved.
— Diagram conventions have been clarified.
— Some definitions in the Glossary have been clarified.
— Consistency between the diagrams of the Functional Entities and supporting
text has been improved.
— A Preservation Watch function has been added to the Preservation Planning
Functional Entity.
— The definition of the Information Package has been updated for consistency.
— Additional preservation techniques have been described explicitly in addition to
Migration.
— Additional types of Archive interaction have been added, including primary-
supporting Archives.
— Annex A is marked as Informative. It had previously erroneously been marked
as Normative.
— Annex B from the previous issue described the relationship of OAIS to other
standards; but its contents were continually out of date as those other
standards develop along different directions and timelines as compared to OAIS
development. Also, subsection 1.5 from the previous issue, which provided a
roadmap to related Standards which could be developed was removed since a
number of those standards are now available. Both have been replaced by
pointers in annex B to informative documents on the CCSDS web site which can
be updated more rapidly.
Any feedback or questions on this document should be directed to the user’s national standards
body. A complete listing of these bodies can be found at www.iso.org/members.html.

CCSDS 650.0-M-3 Page iv December 2024
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CONTENTS
Section Page
1 INTRODUCTION . 1-1

1.1 PURPOSE AND SCOPE . 1-1
1.2 APPLICABILITY . 1-2
1.3 RATIONALE . 1-3
1.4 CONFORMANCE . 1-3
1.5 DOCUMENT STRUCTURE . 1-4
1.6 DEFINITIONS . 1-7

2 OAIS CONCEPTS . 2-1

2.1 GENERAL . 2-1
2.2 OAIS ENVIRONMENT . 2-2
2.3 OAIS INFORMATION . 2-3
2.4 PRESERVATION OBJECTIVES . 2-8
2.5 SUPPLEMENTARY INFORMATION HELD BY THE ARCHIVE . 2-9
2.6 OAIS HIGH-LEVEL EXTERNAL INTERACTIONS . 2-10

3 OAIS RESPONSIBILITIES. 3-1

3.1 OVERVIEW . 3-1
3.2 MANDATORY RESPONSIBILITIES . 3-1
3.3 EXAMPLE MECHANISMS FOR DISCHARGING RESPONSIBILITIES . 3-2

4 DETAILED MODELS . 4-1

4.1 OVERVIEW . 4-1
4.2 FUNCTIONAL MODEL . 4-1
4.3 INFORMATION MODEL. 4-22
4.4 INFORMATION PACKAGE TRANSFORMATIONS . 4-55

5 PRESERVATION PERSPECTIVES . 5-1

5.1 OVERVIEW . 5-1
5.2 DIGITAL MIGRATION . 5-2
5.3 ADDING REPRESENTATION INFORMATION . 5-11
5.4 HANDING OVER TO ANOTHER OAIS . 5-16

6 ARCHIVE INTEROPERABILITY . 6-1

6.1 GENERAL . 6-1
6.2 LEVELS OF INTERACTION BETWEEN OAIS ARCHIVES . 6-2
CCSDS 650.0-M-3 Page v December 2024
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CONTENTS (continued)
Section Page
ANNEX A COMPOSITE FUNCTIONAL VIEW (INFORMATIVE) . A-1
ANNEX B RELATIONSHIP WITH OTHER STANDARDS OR
EFFORTS (INFORMATIVE) . B-1
ANNEX C BRIEF GUIDE TO THE UNIFIED MODELING
LANGUAGE (UML) (INFORMATIVE) . C-1
ANNEX D INFORMATIVE REFERENCES (INFORMATIVE). D-1
ANNEX E A MODEL FOR SOFTWARE USE IN REPRESENTATION
INFORMATION (INFORMATIVE) . E-1
ANNEX F SECURITY CONSIDERATIONS (INFORMATIVE) . F-1
Figure
1-1 Examples of Diagram Conventions . 1-6
2-1 Environment Model of an OAIS . 2-2
2-2 Obtaining Information from Data . 2-4
2-3 Information Package Concepts and Relationships . 2-6
2-4 OAIS Archive External Data . 2-10
4-1 OAIS Functional Entities . 4-1
4-2 Functions of the Ingest Functional Entity . 4-6
4-3 Functions of the Archival Storage Functional Entity . 4-8
4-4 Functions of the Data Management Functional Entity . 4-10
4-5 Functions of the Administration Functional Entity . 4-12
4-6 Functions of the Preservation Planning Functional Entity . 4-15
4-7 Functions of the Access Functional Entity . 4-18
4-8 OAIS Data Flow Diagram . 4-20
4-9 Administration Context Diagram . 4-21
4-10 Information Object . 4-23
4-11 Representation Information Object . 4-26
4-12 Partial General RIN . 4-27
4-13 Example of a Simplified RIN for a FITS File . 4-28
4-14 Information Object Taxonomy . 4-31
4-15 Information Package Contents and Its Associated Package
Description and Packaging Information. 4-39
4-16 Example of an Information Object Made Up of Content
Information and PDI . 4-39
4-17 Information Package Taxonomy . 4-40
4-18 Archival Information Package (AIP) and Its Associated Package
Description and Packaging Information. 4-42
4-19 Preservation Description Information . 4-43
4-20 Package Description and Its Associated AIP . 4-44
CCSDS 650.0-M-3 Page vi December 2024
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CONTENTS (continued)
Figure Page
4-21 Archival Information Package (Detailed View) and Its Associated
Package Description and Packaging Information . 4-45
4-22 Specialization of the AIP . 4-46
4-23 Specialization of the Package Description . 4-47
4-24 Archival Information Unit (AIU) and Its Associated Unit
Description and Packaging Information. 4-48
4-25 Unit Description and Its Associated Archival Information Unit . 4-48
4-26 Archival Information Collections and Its Associated Collection
Description and Packaging Information Logical View . 4-50
4-27 Collection Description and Its Associated Archival Information Collection . 4-52
4-28 Data Management Information . 4-55
4-29 High-Level Data Flows in an OAIS . 4-56
5-1 Conceptual View of Relationships among Names and AIP Components . 5-4
6-1 Cooperating Archives with Mutual Exchange Agreement . 6-4
6-2 Cooperating Archives with Standard Ingest and Access Methods . 6-5
6-3 An OAIS Federation Employing a Common Catalog . 6-6
6-4 Archives with Shared Storage . 6-10
6-5 Example of a Distributed OAIS Archive for Archival Storage . 6-12
6-6 Another Example of a Distributed OAIS Archive for Archival Storage . 6-14
A-1 Composite of Functional Entities . A-2
C-1 Key to UML Relationships . C-1
E-1 Layered Information Model . E-1
Table
4-1 Examples of PDI . 4-36
5-1 CDO Software Roles and Preservation Possible Actions . 5-14

CCSDS 650.0-M-3 Page vii December 2024
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1 INTRODUCTION
1.1 PURPOSE AND SCOPE
The purpose of this document is to define 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.
CCSDS 650.0-M-3 Page 1-1 December 2024
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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.
1.2 APPLICABILITY
The OAIS model in this document may be applicable to any Archive. It is specifically
applicable to organizations, which may themselves be part of larger organizations, with the
responsibility of making information available for the Long Term (as defined in 1.6.2). This
includes organizations with other responsibilities, such as receiving, processing and
distribution in response to programmatic needs.
Organizations may require their information, from the start, to be re-processable to enable the
results created by others to be reproduced, interoperable with other information, and re-used
in new ways. Such organizations will find this document relevant because of the requirement
that, to be preserved, the information must be understandable and usable.
This model is also of interest to those organizations and individuals who create information
that may need Long Term Preservation and those that may need to acquire information from
such Archives.
The model, including the functional and information modelling concepts, is relevant to the
comparison and design of facilities which hold information, on a temporary basis, for two
reasons:
– When taking into consideration the rapid pace of technology changes or possible
changes in a Designated Community, there is the likelihood that facilities, thought to
be holding information on a temporary basis, will in fact find that some or much of
their information holdings will need Long Term Preservation attention.
– Although some facilities holding information may themselves be temporary, some or
all of their information may need to be preserved indefinitely. Such facilities need to
be active participants in the Long Term Preservation effort.
Standards developers are expected to use this model in conjunction with related standards
and community documents as a basis for further standardization in this area. Many related
standards are possible and some have already been developed. Annex B includes links to
websites containing references to a selection of related standards.
This reference model does not specify a design or an implementation. Actual
implementations may group or break out functionality differently.
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1.3 RATIONALE
A tremendous growth in computational power, and in networking bandwidth and
connectivity, has resulted in an explosion in the number of organizations making digital
information available. Transactions among all types of organizations are being conducted
using digital forms that are taking the place of more traditional media such as paper.
Preserving information in digital forms is much more difficult than preserving information in
forms such as paper and film. This is not only a problem for traditional archives, but also for
many organizations that have never thought of themselves as performing an archival
function. Along with the many advantages in terms of, for example, searchability and
replication, the spread of digital technology in every field brings certain disadvantages. The
rapid obsolescence of digital technologies creates considerable technical dangers, particularly
a much greater risk than in the past of losing the possibility of restoring, rendering or
interpreting the information. Ways of avoiding or reducing these dangers will be detailed
throughout this Recommended Practice. Nevertheless, it would be unwise to consider the
problem from a solely technical standpoint. There are also organizational, legal, industrial,
scientific and cultural issues to be considered. To ignore the problems raised by preserving
information in digital forms would lead inevitably to the loss of this information. In addition,
information is more and more easily altered or faked. Ways to be more sure of the
authenticity of information, by knowing its provenance and being sure that it has not been
altered, will help to counter these threats
It is expected that this reference model, by establishing minimum requirements for an OAIS
Archive along with a set of archival concepts, will provide a common framework from which
to view archival challenges, particularly as they relate to digital information. This should
enable more organizations to understand the issues and take the proper steps to ensure Long
Term information preservation. It should also provide a basis for more standardization and,
therefore, a larger market that vendors can support in meeting archival requirements.
1.4 CONFORMANCE
A conforming OAIS Archive implementation shall support, and be able to map to the
components of, the model of information described in 2.3 and 4.3, which provides more
formal definitions of the model using UML. The OAIS Reference Model does not define or
require any particular method of implementation of these concepts.
A conforming OAIS Archive shall fulfil the responsibilities listed in 3.2. Subsection 3.3
provides examples of the mechanisms that may be used to discharge the responsibilities
identified in 3.2. These mechanisms are not required for conformance.
A conformant OAIS Archive may provide additional services that are beyond those
required of an OAIS.
This reference model does not specify a design or an implementation. Actual
implementations may group or break out functionality differently.
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It is assumed that implementers will use this reference model as a guide while developing a
specific implementation to provide identified services and content. This document does not
assume or endorse any specific computing platform, system environment, system design
paradigm, system development methodology, database management system, database design
paradigm, data definition language, command language, system interface, user interface,
technology, or media required for implementation.
The OAIS Reference Model is designed as a conceptual framework in which to discuss and
compare Archives. As such, it attempts to address all the major activities of an information-
preserving Archive in order to define a consistent and useful set of terms and concepts. A
standard or other document that claims to be conformant to the OAIS Reference Model shall
use the terms and concepts defined in the OAIS Reference Model in the same manner.
Subsection 1.6.2 defines OAIS terminology and is normative.
To summarize, to be conformant with OAIS, an Archive must support the basic terminology
specified in section 1.6.2, must be able to map its practices to the OAIS Information Model,
which is defined at very high level in 2.3 and in more detail in 4.3, and must also fulfill the
Mandatory Responsibilities specified in 3.2.
1.5 DOCUMENT STRUCTURE
1.5.1 HOW TO READ THIS DOCUMENT
All readers should read the Purpose and Scope (1.1), Applicability (1.2), and Conformance (1.4)
subsections to obtain a view on the objectives and applicability of the document.
Those who want just an overview of the major concepts should also read OAIS Concepts
(section 2) and OAIS Responsibilities (section 3).
Those who will implement OAIS Archives or administer them should read the entire
document.
1.5.2 ORGANIZATION BY SECTION
Section 1 provides purpose, scope, applicability, and definitions sections typical of many
standards. It also provides rationale for the effort and conformance requirements.
Section 2 provides a high-level overview of the major concepts involved in an OAIS
Archive. It provides a view of the environment of an OAIS Archive and the roles played by
those who interact with it. It discusses what is meant by ‘information’ and what is necessary
to preserve it for the Long Term. It contains key information concepts relevant to OAIS-
conforming implementations.
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Section 3 describes the responsibilities required of an OAIS. Subsection 3.2 defines
mandatory responsibilities an OAIS Archive must discharge in preserving its information,
and 3.3 provides clarifying material of the types of activities that may be needed in many
Archives to discharge these responsibilities.
Section 4 provides model views needed for a detailed understanding of an OAIS Archive. It
breaks down the OAIS into a number of informative abstract functional entities and it
describes some abstract high-level services provided at the interfaces of these entities. It also
provides normative information models using Unified Modeling Language (UML) class
diagrams.
Section 5 provides some perspectives on the issues of information preservation. It also
provides some perspectives on the issues of preserving access services to digital information
using software porting, wrapping, and emulation of hardware.
Section 6 is an introduction to the various alternatives for Archive-to-Archive associations to
provide increased or more cost-effective services.
The annexes B-F are not part of the Recommended Practice and are provided for the
convenience of the reader:
– annex A provides a composite diagram of the detailed functional entities described in 4.2;
– annex B contains pointers to external documents which relates parts of this reference
model to other standards work and provides a guide for development of related
standards;
– annex C provides a brief tutorial on the Unified Modeling Language class diagrams
(UML);
– annex D provides a list of informative references;
– annex E provides a layered model of information;
– annex F provides an overview of security considerations.
1.5.3 DIAGRAM CONVENTIONS
Except where indicated otherwise, diagrams show entities such as people or organizations as
round cornered long rectangles, functions as rectangles with round corners and functional
entities as rectangles with cut corners, with information between them as arrows, and special
information objects as ellipses as illustrated in figure 1-1.
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function
E
N
T
I Functional
T
Entity
I
E
Special
S
Information
Figure 1-1: Examples of Diagram Conventions
To serve as visual clues, consistent colors have been adopted for each Functional Entity and its
component Functions; however, the diagrams do not depend upon these colors to be usable.
1.5.4 TYPOGRAPHICAL CONVENTIONS
There are many terms which are used in this reference model and which need to have well-
defined meanings. These terms are defined in 1.6.2. When first used in the text, they are
shown in bold and are capitalized. Subsequent use employs capitalization only. Because of
their extensive use in this document, the defined terms ‘data’ and ‘information’ will not
always be capitalized unless they are part of another defined term. The defined term ‘archive’
will not be capitalized unless it is used as the equivalent of an ‘OAIS Archive’.
Many diagrams are included throughout this reference model, primarily in sections 4 and 6.
In text discussing the diagrams, block names are capitalized and flows are italicized.
1.5.5 NOMENCLATURE
1.5.5.1 Normative Text
The following conventions apply for the normative specifications in this Recommended
Practice:
a) the words ‘shall’ and ‘must’ imply a binding and verifiable specification;
b) the word ‘should’ implies an optional, but desirable, specification;
c) the word ‘may’ implies an optional specification;
d) the words ‘is’, ‘are’, and ‘will’ imply statements of fact.
NOTE – These conventions do not imply constraints on diction in non-normative text.
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1.6 DEFINITIONS
1.6.1 ACRONYMS AND ABBREVIATIONS
AIC Archival Information Collection
AIP Archival Information Package
AIU Archival Information Unit
API Application Programming Interface
ASCII American Standard Code for Information Interchange
CCSDS Consultative Committee for Space Data Systems
CD-ROM Compact Disk-Read Only Memory
CDO Content Data Object
CPU Central Processing Unit
CRC Cyclic Redundancy Check
CSV Comma Separated Value
DBMS Data Base Management System
DIP Dissemination Information Package
DRM Digital Rights Management
FITS Flexible Image Transport System
FTP File Transfer Protocol
HFMS Hierarchical File Management System
HTTP HyperText Transfer Protocol.
ID Identifier
IEEE Institute of Electrical and Electronics Engineers
IETF Internet Engineering Task Force
ISBN International Standard Book Number
ISO International Organization for Standardization
MPEG Moving Picture Experts Group
OAIS Open Archival Information System
PDF Portable Document Format
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PDI Preservation Description Information
QA Quality Assurance
RFC Request For Comment
SIP Submission Information Package
TCP/IP Transmission Control Protocol/Internet Protocol
UML Unified Modeling Language
USB Universal Serial Bus
VHS Video Home System
WWW World Wide Web
XFDU XML Formatted Data Unit
XML eXtensible Markup Language
1.6.2 TERMINOLOGY
This subsection is normative.
There are many terms which are used in this reference model and which need to have well-
defined meanings. These terms are defined in this subsection. When first used in the text,
they are shown in bold and are capitalized. Subsequent use employs capitalization only.
In other CCSDS documents the terms such as ‘service’ and ‘object’ have different definitions
from those used here. Where confusion may arise then the terms from this document may be
prefixed with ‘OAIS’.
As this reference model is applicable to all disciplines and organizations that do, or expect to,
preserve and provide information in digital form, these terms cannot match all of those familiar
to any particular discipline (e.g., traditional archives, digital libraries, science data centers).
Rather, the approach taken is to use terms that are not already overloaded with meaning so as to
reduce conveying unintended meanings. Therefore, it is expected that all disciplines and
organizations will find that they need to map some of their more familiar terms to those of the
OAIS Reference Model. This should not be difficult and is viewed as a contribution, rather
than a deterrent, to the success of the reference model. For example, archival science focuses
on preservation of the ‘record’. This term is not used in the OAIS Reference Model, but one
mapping might approximately equate it with ‘Content Information within an Archival
Information Package’ (see definitions below, as well as 2.3 and 4.3 for context).
Access Aid: A software program or document that allows Consumers to locate, analyze,
order or retrieve information from an OAIS.
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Access Collection: A collection of AIPs that is defined by a Collection Description but for
which there is no Packaging Information for the collection in Archival Storage.
Access Functional Entity: The OAIS functional entity that provides the services and
functions that support Consumers in determining the existence, description, location and
availability of information stored in the OAIS, and allowing Consumers to request and
receive information products.
Access Rights Information: The information that identifies the access restrictions pertaining
to the Content Data Object, including the legal framework, licensing terms, and access
control. It contains the access and distribution conditions stated within the Submission
Agreement, related to both preservation (by the OAIS) and final usage (by the Consumer). It
also includes the specifications for the application of rights enforcement measures.
Access Software: A type of software that presents part of or all of the information content of
an Information Object in forms understandable to or usable by humans or their proxy
systems.
Ad-hoc Order: A request that is generated by a Consumer for information the OAIS has
indicated is currently available.
Administration Functional Entity: The OAIS functional entity that provides the services
and functions needed to control the operation of the other OAIS functional entities on a day-
to-day basis.
AIP Edition: An AIP whose Content Information or Preservation Description Information
has been subject to an upgrade or improvement which was not required for preservation. An
AIP edition is not considered to be the result of a Migration.
AIP Version: An AIP resulting from changing the Content Information or Preservation
Description Information of a source AIP, in order to preserve the information. An AIP
Version is considered to be the result of a Migration.
Archival Information Collection (AIC): An Archival Information Package whose Content
Information is an aggregation of other Archival Information Packages.; its PDI must include
a description of the collection criteria and process.
NOTE – At a minimum all OAISes can be viewed as having at least one AIC which
contains all the AIPs held by the OAIS.
Archival Information Package (AIP): An Information Package, consisting of the Content
Information and the associated Preservation Description Information (PDI), which is
preserved within an OAIS.
Archival Information Unit (AIU): An Archival Information Package where the Content
Information does not include any other Archival Information Packages. An AIU can consist
of multiple digital objects, for example, multiple files.
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Archival Storage Functional Entity: The OAIS functional entity that provides the services
and functions used for the storage and retrieval of Archival Information Packages.
Archive: An organization that intends to preserve information for access and use by a
Designated Community.
Associated Description: The information describing the content of an Information Package
from the point of view of a particular Access Aid.
Authenticity: The degree to which a person (or system) regards an object as what it is
purported to be. Authenticity is judged on the basis of evidence.
Collection Description: A type of Package Description that is specialized to provide
information about an Archival Information Collection (or an Access Collection) for use by
Access Aids.
Common Services: The supporting services such as inter-process communication, name
services, temporary storage allocation, exception handling, security, and directory services
necessary to support the OAIS.
Consumer: The role played by those persons, or client systems, who interact with OAIS
services to find preserved information of interest and to access that information in whatever
level of detail is allowed. In addition to the normally expected entities outside the OAIS, this
can also include other OAISes, as well as internal OAIS persons or systems.
Content Data Object: The Data Object, that together with associated Representation
Information, comprises the Content Information.
Content Information: A set of information that is the original target of preservation. It is an
Information Object composed of its Content Data Object and its Representation Information.
Context Information: The information that documents the relationships of the Content Data
Object to its environment. This includes why the Content Data Object was created and how it
relates to other Content Data Objects.
Co-operating Archives: Those Archives that have Designated Communities with related
interests. They may order and ingest data from each other. At a minimum, Co-operating
Archives must agree to support at least one common Submission Information Package (SIP)
and Dissemination Information Package (DIP) for inter-Archive requests.
Data: A reinterpretable representation of information in a formalized manner suitable for
communication, interpretation, or processing.
NOTE – Examples of data include a sequence of bits, a table of numbers, the characters on a
page, the recording of sounds made by a person speaking, or a moon rock specimen.
Data Dictionary: A formal repository of terms used to describe data.
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Data Dissemination Session: A delivery of media or a single telecommunications session
that provides Data to a Consumer. The Data Dissemination Session format/contents is based
on a data transfer specification negotiated between the OAIS and the Consumer in the Order
Agreement. This specification identifies the logical constructs used by the OAIS and how
they are represented on each media delivery or in the telecommunication session.
Data Management Data: The data created and stored in Data Management persistent
storage that refer to operation of an Archive.
NOTE – Examples of Data Management Data are accounting data for Consumer billing
and authorization, policy data, Event Based Order (subscription) data for
repeating requests, preservation process history data, and statistical data for
generating reports to Archive management.
Data Management Functional Entity: The OAIS functional entity that provides the
services and functions for populating, maintaining, and accessing both Descriptive
Information which identifies and documents Archive holdings and administrative data used
to manage the Archive.
Data Object: Either a Physical Object or a Digital Object.
Data Submission Session: A delivery of media or a single telecommunications session that
provides Data to an OAIS. The Data Submission Session format/contents is based on a data
transfer specification negotiated between the OAIS and the Producer in the Submission
Agreement. This specification identifies the logical constructs used by the Producer and how
they are represented on each media delivery or in the telecommunication session.
Derived AIP: An AIP generated by extracting or aggregating information from one or more
source AIPs.
Descriptive Information: An Information Object which is a set of information, consisting
primarily of Package Descriptions, which is provided to Data Management to support the
finding, ordering, and retrieving of OAIS information holdings by Consumers.
Designated Community: An identified group of potential Consumers who should be able to
understand a particular set of information in ways exemplified by the Preservation
Objectives. The Designated Community may be composed of multiple user communities. A
Designated Community is defined by the Archive and this definition may change over time.
Digital Migration: The transfer of digital information, while intending to preserve it, within
the OAIS. It is distinguished fr
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