Open Archival Information Systems Reference Model ISO 14721:2003
(revised as ISO 14721:2012 and is due for a further revision in 2017 and you can get involved with this process by contributing to this community wiki.
ISO 14721:2003 defines the OAIS Model as: an archive, consisting of an organization of people and systems, that has accepted the responsibility to preserve information and make it available for a Designated Community, where the information being maintained is 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.
The Open Archival Information System Reference Model: Introductory Guide (PDF 372KB) by Brian F. Lavoie 2004 (From the Digital Preservation Coalition Technology Watch Report Series)Documentation ISO from their original developers: Consultative Committee for Space Data Systems, here (first version) and here (second version).