oais1.jpgNoted from the OAIS model.

SIPs are sent to the OAIS archive by Producers. Producers are authors, organisations or even programs which deliver documents to the OAIS. Some submissions will have insufficient Representation Information or Preservation Description Information to meet stringent AIP requirements, which is why they cannot necessarily be AIPs.

The form of the SIP will typically be negotiated between the Producer and the OAIS (2.2.3). Most SIPs will have some Content Information and some PDI, but it may require several submissions to form an AIP. If there are multiple SIPs which use the same Representation Information it is likely that this RI will only be provided once to the OAIS (4.2.2.2).

Ideally there should be a submission agreement between the Producer and the OAIS, specifying criteria like file formats, subject matter, ingest schedule, access restrictions, verification protocols, etc (2.3.2). “Considerable iteration may be required to agree on the right information to be submitted, and to get it into forms acceptable to the OAIS” (3.2.1). You also need to negotiate legal aspects, such as authority to migrate the Content Information to new representation forms (3.2.2). Data submission formats, procedures and deliverables must be documented in the OAIS’s data submission policies (4.1.1.5).

The Ingest entity (4.1.1.2) in an OAIS accepts SIPs, performs QA on them, and generates an AIP. QA might involve checksums or cyclic redundancy checks. If there are errors in the SIP submission then Ingest will request a resubmission. Ingest then transforms the SIPs into AIPs, which might include file format conversion, reorganisation, transfer to different media etc. “An OAIS is not always required to retain the information submitted to it in precisely the same format as in the SIP” (4.3.2). At the very least it will add a unique identifier.

Section 4.3.2 has some examples of SIP to AIP data transformations, such as one-to-one, one -to-many or many-to-one.

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