PROV-ISSUE-665: PROV Identifier conventions clarification [XML Serialization]

PROV-ISSUE-665: PROV Identifier conventions clarification [XML Serialization]

http://www.w3.org/2011/prov/track/issues/665

Raised by: Stephan Zednik
On product: XML Serialization

>From Luc's feedback on PROV-XML WG Note:

As part of the design section, we should talk about the identifier
conventions, especially, that they go beyond what XML does usually.

  1. All PROV identifiers are expressed as QNames in prov-xml.
 
  2. PROV mandates that QNames should be mappable to a uri by concatenating
     namespace uri to local name.

  3. Note the restrictive nature of QNames, and some PROV-N identifiers, 
     such as ex:001 are not valid QNames.  Hence, from an inter-operability
     viewpoint across representations, implementers should aim to express identifiers
     as valid QNames rather than more permissive QualifiedNames in PROV-N.