Workbook on Digital Private Papers > Administrative and preservation metadata > Preservation metadata
Preservation metadata
Using Metadata Encoding and Transmission Standard (METS) for preservation metadata
Like many other digital preservation initiatives, Paradigm used METS as a manner of uniting various kinds of metadata with digital objects. METS and XML-encoded PREMIS could be combined in several ways. Some of the possible options are outlined below:
Option 1 - compound\
It is possible to hold all the metadata about an archive in a single METS file, perhaps something along the following lines:
- A MODS record for each item in the dmdSec, based on automatically derived descriptive metadata, allowing the archive to establish some basic intellectual control over the archive.
- A PREMIS object record for each item in amdSec/techMD.
- A type-specific metadata record for each item (e.g. MIX, textMD) in amdSec/techMD.
- A PREMIS rights record in amdSec/rightsMD.
- PREMIS event records for each event in amdSec/digiprovMD.
- PREMIS agent records relating to event record(s) in amdSec/digiprovMD.
- A fileSec inventory, with fileGrp rules for:
- Intellectual Entities.
- Representations of Intellectual Entities.
- Files.
- A structMap detailing the original order of the Intellectual Entities in the archive.
- Several structMap sections detailing the structure of each Representation of an Intellectual Entity.
Advantages
- Requires only one METS file.
Disadvantages
- The resulting METS file would be enormous and difficult to work with.
- The resulting METS file would be complex, especially as new Representations, Files, events and agents are created through migrations.
- Requires careful planning and control over the assignment of identifiers and linking mechanisms.
Option 2 - atomistic
Split up the archive into numerous, smaller, METS files and use the linking mechanisms in METS and PREMIS to connect these.
Option 2a
Create separate METS files for:
- Intellectual Entities.
- Representations of Intellectual Entities.
- Files.
- Agents.
- Events.
- Rights.
Option 2b
Create separate METS files for:
- Intellectual Entities, which include metadata for:
- Representations of the intellectual entity.
- Files which make-up the Representation(s).
- Agents.
- Events.
- Rights.
Option 2c
Create separate METS files for:
- Intellectual Entities, which include metadata for:
- Representations of Intellectual Entities.
- Files.
- Agents.
- Events.
- Rights.
Option 2d
Create separate METS files for:
- Intellectual Entities.
- Representations of Intellectual Entities, which include metadata for:
- Files.
- Agents.
- Events.
- Rights.
Advantages
- Results in smaller METS file sizes.
- Results in simpler METS files from day one and through subsequent migration pathways.
- Avoids unnecessary duplication of metadata: where the same metadata (e.g. rights) relates to numerous objects, it is possible to link from all of those objects to a single METS file containing the common information.
Disadvantages
- A number of METS files may be needed to assemble a complete AIP for transfer to another repository.
- Requires careful planning and control over the assignment of identifiers and linking mechanisms.
Ids
Much in METS and PREMIS is dependent on ids. The repository must develop schemes for automatic assignation of identifiers to metadata, files, rights, agents and events; such schemes must take account of various ID-related issues, including scalability. See earlier in this chapter for more on Persistent Identifiers.
