3.5 Design – Element sets
3.5.1 A metadata element set comes next in the overall design. Here three main categories or groupings of metadata are commonly described:
3.5.1.1 Descriptive Metadata, which is used in the discovery and identification of an object.
3.5.1.2 Structural Metadata, which is used to display and navigate a particular object for a user and includes the information on the internal organization of that object, such as the intended sequence of events and relationships with other objects, such as images or interview transcripts.
3.5.1.3 Administrative Metadata, which represents the management information for the object (such as the namespaces that authorise the metadata itself), dates on which the object was created or modified, technical metadata (its validated content file format, duration, sampling rate, etc.), rights and licensing information. This category includes data essential to preservation.
3.5.2 All three categories, descriptive, structural and administrative, must be present regardless of the operation to be supported, though different sub-sets of the data may exist in any file or instantiation. So, if the metadata supports preservation – “information that supports and documents the digital preservation process” (PREMIS) – then it will be rich in data about the provenance of the object, its authenticity and the actions performed on it. If it supports discovery then some or all of the preservation metadata will be useful to the end user (i.e. as a guarantor of authenticity) though it will be more important to elaborate and emphasise the descriptive, structural and licensing data and provide the means for transforming the raw metadata into intuitive displays or in readiness for harvesting or interaction by networked external users. Needless to say, an item that cannot be found can neither be preserved nor listened to so the more inclusive the metadata, with regard to these operations, the better.
3.5.3 Each of those three groupings of metadata may be compiled separately: administrative (technical) metadata as a by-product of mass-digitization; descriptive metadata derived from a legacy database export; rights metadata as clearances are completed and licenses signed. However, the results of these various compilations need to be brought together and maintained in a single metadata instance or set of linked files together with the appropriate statements relating to preservation. It will be essential to relate all these pieces of metadata to a schema or DTD (Document Type Definition) otherwise the metadata will remain just a ‘blob’, an accumulation of data that is legible for humans but unintelligible for machines.
