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Revision as of 09:33, 27 September 2007 by Ryan Scherle (talk | contribs) (Open Questions)

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We must determine the best possible identifier scheme for data in the repository. Once we implement a scheme, it will be nearly impossible to change. The DSpace Lessons Learned page tells us that "The persistent identifier for content is the single best selling point for DSpace when talking with faculty."

Possible Identifier Schemes


Handles are native to DSpace and supported by Fedora.


  • Must register each identifier with a central service.

DOI (Digital Object Identifier)

DOIs are one particular implementation of handles, used widely in the publishing industry. One difference is that the DOI system mandates metadata that must be associated with every DOI, while "plain" handles (and most other ID systems) leave metadata up to the user.

An old post from Rod Page suggests using DOIs for manuscript-level information and handles for more granular information. This would hold down costs, but could be messy.


  • Must register each identifier with a central service.
  • Must pay to register each identifier

LSID (Life Science Identifier)

LSID is a URN identifier scheme.


  • There are no known sites that use LSIDs as their primary identifier, though a few sites (available from the LSID homepage) can resolve LSIDs into their identifier scheme.
  • LSIDs seem to have fallen out of favor as people have realized that URLs can be identifiers, and tools for other identifier schemes have improved.
  • Unclear whether a central resolution authority really exists
  • Community is much smaller than for other identifier schemes
  • The W3C has written a document that shows non-http schemes aren't any better than http-based schemes.


UNF is a content-based identifier for data objects, somewhat like a fingerprint.


Define our own identifier system, and add DOIs/Handles as appropriate.

  • "Handle-like" identifiers are handed out for free by DSpace, so why not use them?

Identifier schemes in use

  • CiteSeer: custom
  • ChemXSeer: doi, custom
  • GenBank: accession
  • PubMed: custom
  • GBIF: custom
  • KNB: custom
  • OceanPortal: accession
  • Morphbank: accession
  • MorphoBank: accession
  • National Climatic Data Center: custom
  • Paleobiology Database: accession
  • TreeBASE: custom
  • World Data Center: doi
  • PDB: custom, doi
  • ACM: doi
  • Dlib magazine: doi


  • We need to look at other repositories (genbank, treebase, gbif, etc.) to see what types of identifiers they are using.
  • There is a section on identifiers in the grant proposal....

Open Questions

  1. Is it possible to create sub-parts of a DOI? For example: http://dx.doi.org/1234/abc1234/subpart1. This would allow us to limit the number of DOIs registered, but provide access at any granularity we wish.
  2. Is it possible to get the same "institution identifier" in both the DOI and CNRI handle systems?
  3. Do we want to assign identifiers to particular bitstreams, like LSID does? This seems ripe for disaster. While we want software to be able to work with a data object in a consistent manner (we don't want to suddenly change the format out from under them), we also don't want to preserve data formats that are definitely dead (in 50 years, we won't have tools to parse an Excel 2003 file, or the current form of a NEXUS file).