303 and concept URIs - towards GUIDs for all

I've bookmarked some stuff relevant to the issue of what HTTP URIs identify. This concerns whether a URI identifiers something in the real world (or a concept), or a document. The "303" refers to the HTTP code returned if the URI is a concept, not a document. The whole topic is a mess, but I need to get to grips with it as I'm working on a service to assign URIs to just about any biologically interesting object. Sigh.

Harvesting handles

Finally discovered how to get metadata from DSpace-hosted items, such as the AMNH's Scientific Publications. They have an OAI interface, so that the URL http://digitallibrary.amnh.org/dspace-oai/request?
verb=GetRecord
&metadataPrefix=oai_dc
&identifier=oai:digitallibrary.amnh.org:2246/1999 will retrieve XML metadata for the record hdl:2246/1999 -- in this case, number 2578 of the American Museum novitates.

Oh, and the Simile project already has a OAI to RDF XSLT stylesheet (found courtesy of Leigh Dodds OAI bookmarks on del.icio.us).

Almost forgot, I stumbled across this information at Celestial.