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- Descriptive metadata: information about the intellectual content of a digital object, which is used to aid identification and discovery of the object by the researcher.
- Structural metadata: information about the relationships between digital objects, which can be very complex in a large hybrid personal archive. Structural metadata also supports the display and navigation of digital objects by users.
- Administrative metadata: information needed by the repository for the long-term management of a digital object, including information about an object's creation, technical information such as file formats, provenance information and information about intellectual property rights.