More info on XMP

Hi all,

some more information about XMP, which should close action-92.

- in part 3 of the XMP specification there  are mappings to existing formats
http://www.adobe.com/devnet/xmp/pdfs/XMPSpecificationPart3.pdf
which it seems we have not taken into account yet
- there is no RDF schema for XMP, and Adobe tools (all?) process XMP not in
the XML/RDF serialization but in another, XMP specific format.
- XMP does not make use of the inferences one could draw from an RDF Schema
or other RDF formal semantics

Best,

Felix