4.2.5.1 Tools or methods to identify the file types of all objects

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4.2.5.1 Tools or methods to identify the file types of all objects
Status Ready for review
Compliance Rating Fully compliant
Responsible

The repository shall have tools or methods to ensure that the requisite Representation Information is persistently associated with the relevant Data Objects.

Supporting Text

This is necessary in order to ensure that the repository’s digital objects are understandable to the Designated Community.

Examples of Meeting the Requirement

Subscription or access to registries of Representation Information (including format registries); viewable records in local registries (with persistent links to digital objects); database records that include Representation Information and a persistent link to relevant digital objects.

Discussion

These tools and resources can be held internally or can be shared via, for example, a trusted set of registries. However, this requirement does not demand that each repository has such tools and resources, merely that it has access to them. For example a repository may access external registries. Any such registry is a specialized type of repository, which itself must be certified/trustworthy. The repository may use these types of standardized, authoritative information sources to identify and/or verify the Representation Information components of Content Information and PDI. This will reduce the long-term maintenance costs to the repository and improve quality control. Sometimes there is both general Representation Information (e.g., format information) and specific Representation Information (e.g., meanings of individual fields within a dataset). Often the general information will be available in an external repository, but the local repository may need to maintain the instance-specific information. It is likely that many repositories would wish to keep local copies of relevant Representation Information; however, this may not be practical in all cases. Even where a repository strives to keep all such information locally there may be, for example, a schedule of updates which means that until an update is performed, the local Representation Information is incomplete. This may be regarded as a kind of local caching of, for example, the Representation Information held in registries. Alternatively one may say that in these cases, the use of international registries is not meant to replace local registries but instead serve as a resource to verify or obtain independent, authoritative information about any and all Representation Information. Good practice suggests that any locally held Representation Information should also be made available to other repositories via a trusted registry. In addition any item of Representation Information should itself have adequate Representation Information to ensure that the Designated Community can understand and use the data object being preserved.

Evidence Provided

APTrust saves all data objects as Generic Files. Each Generic File has a file format attribute containing file type information. See the section File Resource for more information.