Heratio Help Center article. Category: Digital Preservation.
Preservation metadata: PREMIS and METS
Why preservation metadata matters
Descriptive metadata tells people what a record is so they can find it. Preservation metadata tells the archive what it needs to keep the file alive and prove it is authentic - its format, its checksum, and the full history of everything done to it. Two international standards do this work in Heratio: PREMIS and METS.
PREMIS - the preservation history
PREMIS (version 3.0) records four things about preserved content:
- Objects - the files, with their format, size, and checksum.
- Events - every action taken: ingest, fixity check, virus scan, format identification, normalisation, migration, replication. Each has a date and an outcome.
- Agents - the people and software (for example the format-identification tool) responsible.
- Rights - the permission basis for preservation actions.
In Heratio, every preservation action you run is written as a PREMIS event. You
can browse the full event history at /admin/preservation/events, and an
administrator can export a PREMIS 3.0 XML document for any record.
METS - the package wrapper
METS is an XML container that bundles all the metadata for a package into one structured file: descriptive metadata, technical and rights metadata, the PREMIS preservation history, the list of files, and the structure tying them together. Heratio produces METS as part of building OAIS packages, and tailors it to the package type:
- An AIP (archival copy) carries the full PREMIS history.
- A DIP (public access copy) deliberately leaves the PREMIS history out, so no forensic detail or private information is exposed.
Heratio can also read Archivematica-style METS on ingest, so packages produced by other preservation systems can be brought in.
See also
- Digital preservation overview (help)
- OAIS packages: SIP, AIP, DIP (help)
- Fixity and checksums (help)