126.96.36.199 Distinguishing AIP Versions, AIP Editions and Derived AIPs
Unless a Digital Migration involves Transformation, it is not considered to create a new AIP Version and it is not required that its PDI be updated. In other words, the AIP version is considered to be independent of Refreshment, Replication, and Repackaging that does not affect the Content Information or PDI. This does not mean that the OAIS does not track such migrations; rather it is not required to update the PDI as part of such tracking. It is expected that the OAIS will verify that such migration have not altered the Content Information or PDI and that any repackaging still binds the same components with the same relationships. It is also expected that the OAIS will track the existence of these events, including the verifications made, as a part of its larger operational provenance as this will lend additional evidence concerning the Authenticity of its holdings. If such migration processes are carried out entirely within Archival Storage, the AIP ID remains the same and there is no implied impact to Associated Descriptions or Access Aids.
A Digital Migration that involves Transformation results in a new version of the AIP as defined in 188.8.131.52. In this case, the PDI needs to be updated to identify the source AIP and its version, and to describe what was done and why. The new AIP is viewed as a replacement for the source AIP where the information has been preserved to the maximum extent practical. The AIP is also new, and the Associated Description must be updated. This does not imply any changes are needed to Access Aids unless they have been implemented with ‘hardcoded’ AIP IDs.
An AIP may, in some environments, be subject to upgrading or improvement over time. This is not a Digital Migration in that the intent is not to preserve information, but to increase or improve it. This type of AIP change may be referred to as creating a new AIP Edition. The AIP Edition may or may not be viewed as a replacement for the source AIP, but it may be of historical interest to retain the previous AIP. This also results in a new AIP ID with the same impacts on Associated Descriptions and Access Aids as a Digital Migration Transformation.
An OAIS may also find it convenient to provide an AIP that is derived from an existing AIP. It may do this by extracting some information, or by aggregating information from multiple AIPs, to better serve Consumers. This type of resulting AIP may be referred to as a Derived AIP. It does not replace any of the AIPs that it was derived from and it is not a result of a Digital Migration. This also results in a new AIP ID and a new Associated Descriptions. This may also require updates to, or new, Access Aids depending on how they have been implemented.
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