The repository shall have unique identifiers.

This is necessary in order to ensure that each AIP can be unambiguously found in the future. This is also necessary to ensure that each AIP can be distinguished from all other AIPs in the repository.

Documentation describing naming convention and physical evidence of its application (e.g., logs).

A repository needs to ensure that there is in place an accepted, standard naming convention that identifies its materials uniquely and persistently for use both in and outside the repository. The ‘visibility’ requirement here means ‘visible’ to repository managers and auditors. It does not imply that these unique identifiers need to be visible to end users or that they serve as the primary means of access to digital objects. Ideally, the unique ID lives as long as the AIP; if it does not, there must be traceability. Subsection 4.2.1 requires that the components of an AIP be suitably bound and identified for long-term management, but places no restrictions on how AIPs are identified with files. Thus, in the general case, an AIP may be distributed over many files, or a single file may contain more than one AIP. Therefore identifiers and filenames may not necessarily correspond to each other. Documentation must represent these relationships.

The practice is that if a Bag is submitted with the same name the system will override the original bag with the newly submitted bag. That is intentional in why the system does that. The system puts the requirement to maintain the uniqueness on the contributor of the Bag. If the contributor creates a bag with the same name but new files, then the contributor end up with a bag that has the sum of all the files.

See the section Using APTrust#Updating and Bagging specifications for additional information.