Workbook on Digital Private Papers > Administrative and preservation metadata > Preservation metadata
Preservation metadata
The PREMIS data model
Although PREMIS builds on the framework established by the OAIS model, the terminology of its Data Dictionary differs somewhat to that of OAIS; the authors attribute this to the transition from conceptual framework (OAIS) to an implementation (PREMIS). The PREMIS data model is composed of five 'entities' relevant to digital preservation. These entities are:
- Intellectual Entities - the conceptual entity, introduced earlier, that can be represented by one or more digital files. Intellectual Entities may also contain other Intellectual Entities (e.g. web pages could be considered sub Intellectual Entities of a website) and may have multiple digital Representations (e.g. a single web page could have one Representation composed of HTML and JPEG files, and another as a PDF file). PREMIS does not define semantic units for Intellectual Entities; these were deemed out of scope because existing descriptive metadata standards tend to be domain-specific and several already exist.
- Object - a discrete unit of information in digital form.
- Event - an action involving at least one Object or Agent known to the repository.
- Agent - person, software or organisation associated with a preservation Event in the life of an Object.
- Rights - assertion of rights pertaining to an Object or Agent in the repository.
The entities defined by PREMIS have relationships with one another. To facilitate these relationships, each entity has an identifier which can be used to point to it from another entity. The arrows in the diagram below show the direction of these relationships.
