Another GUID system that might be of interest is ARK (http://www.cdlib.org/inside/diglib/ark/). The site describing this approach has a nice discussion of the issues surrounding persistent identifiers, and various solutions such as DOIs and URNs (of which LSIDs are an example). I think this system should be looked at closely, before we limit discussion to DOIs or LSIDs. Regards Rod Professor Roderic D. M. Page Editor, Systematic Biology DEEB, IBLS Graham Kerr Building University of Glasgow Glasgow G12 8QP United Kingdom Phone: +44 141 330 4778 Fax: +44 141 330 2792 email: r.page@bio.gla.ac.uk web: http://taxonomy.zoology.gla.ac.uk/rod/rod.html reprints: http://taxonomy.zoology.gla.ac.uk/rod/pubs.html Subscribe to Systematic Biology through the Society of Systematic Biologists Website: http://systematicbiology.org Search for taxon names at http://darwin.zoology.gla.ac.uk/~rpage/portal/