3.8 Structural Metadata – METS

3.8.1     Time-based media are very often multimedia and complex. A field recording may consist of a sequence of events (songs, dances, rituals) accompanied by images and field notes. A lengthy oral history interview occupying more than one .wav file may also be accompanied by photographs of the speakers and written transcripts or linguistic analysis. Structural metadata provides an inventory of all relevant files and intelligence about external and internal relationships including preferred sequencing, e.g. the acts and scenes of an operatic recording. METS (Metadata Encoding and Transmission Standard, current version is 1.7) with its structural map (structMap) and file group (fileGrp) sections has a recent but proven track record of successful applications in audiovisual contexts (see fig. 3).

METS components

Fig 3: components of a METS instance and one possible set of relationships among them

3.8.2     The components of a METS instance are:     A header describes the METS object itself, such as who created this object, when, for what purpose. The header information supports management of the METS file proper.     The descriptive metadata section contains information describing the information resource represented by the digital object and enables it to be discovered.     The structural map, represented by the individual leaves and details, orders the digital files of the object into a browsable hierarchy.     The content file section, represented by images one through five, declares which digital files constitute the object. Files may be either embedded in the object or referenced.     The administrative metadata section contains information about the digital files declared in the content file section. This section subdivides into: technical metadata, specifying the technical characteristics of a file source metadata, specifying the source of capture (e.g.,direct capture or reformatted 4 x 5 transparency) digital provenance metadata, specifying the changes a file has undergone since its birth rights metadata, specifying the conditions of legal access.     The sections on technical metadata, source metadiata, and digital provenance metadata carry the information pertinent to digital preservation.     For the sake of completeness, the behaviour section, not shown above in Fig. 2, associates executables with a METS object. For example, a METS object may rely on a certain piece of code to instantiate for viewing, and the behavior section could reference that code.

3.8.3     Structural metadata may need to represent additional business objects: user information (authentication) rights and licenses (how an object may be used) policies (how an object was selected by the archive) services (copying and rights clearance) organizations (collaborations, stakeholders, sources of funding).

3.8.4     These may be represented by files referenced to a specific address or URL. Explanatory annotations may be provided in the metadata for human readers.