The term Open Archival Information System (or OAIS) refers to the ISO OAIS Reference Model for an OAIS. This reference model is defined by recommendation CCSDS 650.0-M-3 of the Consultative Committee for Space Data Systems; this text is identical to ISO 14721:2025. The CCSDS's purview is space agencies, but the OAIS model it developed has proved useful to other organizations and institutions with digital archiving needs. OAIS, known as ISO 14721:2025, is widely accepted and utilized by various organizations and disciplines, both national and international, and was designed to ensure preservation. The OAIS standard, published in 2005, is considered the optimum standard to create and maintain a digital repository over a long period of time. The OAIS model can be applied to various archives, e.g., open access, closed, restricted, "dark", or proprietary. 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, including support for new media and data formats, or with a changing user community. "Long term" may extend indefinitely. The OAIS defines a long period of time as any length of time that might be impacted by changing technologies and the changing of "Designated Community," e.g., any group of consumers capable of understanding the information. This length of time can be indefinite. The archive defines the community and that definition is not fixed. The "O" in OAIS represents the "open way the standard was developed", and does not represent "open access", or the usage of the term open in the Open Definition or Open Archives Initiative. The "I" in OAIS represents "information", meaning data that can be shared or exchanged. 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 archived materials. Therefore, the model accommodates information that is inherently non-digital (e.g., a physical sample), but the modeling and preservation of such information is not addressed in detail. As strictly a conceptual framework, the OAIS model does not require the use of any particular 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 for an archive to be compliant. Its aim is to set the standard for the activities that are involved in preserving a digital archive rather than the method for carrying out those activities. The acronym OAIS should not be confused with OAI, which is the Open Archives Initiative.
The OAIS environment and information model
The OAIS environment involves the interaction of four entities: producers of information, consumers of information (or the designated community), management, and the archive itself. The management component of the OAIS environment is not an entity that carries out day-to-day maintenance of an archive but a person or group that sets policies for the content contained in the archive. The OAIS model also defines an information model. Physical or digital items which contain information are known as data objects. Members of the Designated Community for an archive should be able to interpret and understand the information contained in a data object either because of their established knowledge base or with the assistance of supplementary "representation information" that is included with the data object. An information package includes the following information objects:
Content Information: this includes the data object and its representation information Preservation Description Information: contains information necessary to preserve its affiliated content information (such as information about the item's provenance, unique identifiers, a Checksum or other authentication data, etc.) Packaging Information: holds the components of the information package together Descriptive Information: metadata about the object which allows the object to be located at a later time using the archive's search or retrieval functions There are three types of information package in the OAIS reference model:
Submission Information Package (SIP): which is the information sent from the producer to the archive Archival Information Package (AIP): which is the information stored by the archive Dissemination Information Package (DIP): which is the information sent to a user when requested These three information packages may or may not be identical to each other.
The functional model
There are six functional entities in an OAIS:
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