The Reference Model for Open Archival Systems is an ISO standard (ISO 14721) which is “now adopted as the “de facto” standard for building digital archives” (NSF report Cyberinfrastructure Vision for 21st Century Discovery).
OAIS provides important concepts which are necessary for preserving all kinds of digitally encoded information. It also provides a large number of terms which are useful to describe repositories.
The standard is available from ISO (www.iso.ch) and is also available free from CCSDS (www.ccsds.org). The standard was originally released in 2002 but an update has been produced – this has completed its ISO review and was published as a standard in 2012. The updated document is available here.