B4.3 Repository preserves the Content Information of archival objects (i.e., AIPs).
The repository must be able to demonstrate that the AIPs faithfully reflect what was captured during ingest and that any subsequent or future planned transformations will continue to preserve that aspect of the repository’s holdings.
This requirement assumes that the repository has a policy specifying that AIPs cannot be deleted at any time. This particularly simple and robust implementation preserves links between what was originally ingested, as well as new versions that have been transformed or changed in any way. Depending upon implementation, these newer objects may be completely new AIPs or merely updated AIPs. Either way, persistent links between the ingested object and the AIP should be maintained.
Evidence: Policy documents specifying treatment of AIPs and whether they may ever be deleted; ability to demonstrate the chain of AIPs for any particular digital object or group of objects ingested; workflow procedure documentation.
ICPSR has a pretty good story to tell here.
AIPs are available as read-only content available to staff. Only system administrators have write access to AIPs, and we try to limit the opportunity for accidental deleting or corrupting as much possible. This means that AIPs are stored in a single container, and that container isn't particularly accessible. The read-only access is granted by a special-purpose web application that runs inside ICPSR's Secure Data Environment (which should be the topic of a future post).
ICPSR's core business process generates new AIPs, and these never overwrite an existing AIP. It is rather like software revision control where new versions just keep getting created. Although in the case of our AIPs we are not storing merely the changes between version N and N + 1; we are storing the complete version of each.
We have extensive workflow procedure documentation. A gent named Cole Whiteman is the author (artist?) for almost of the documents, and they are the products of many hours of conversation and whiteboarding with the ICPSR staff responsible for producing the content that ends up in AIPs.