[model] Proposal: Allow motivatedBy on SpecificResource

Currently the motivation for an Annotation is associated only with the
Annotation, however the different bodies of a single Annotation may have
different motivations for their inclusion.

The current model:  http://www.w3.org/TR/annotation-model/#motivations

Use cases that have come up include:
* A single annotation that has a body that is the replacement edit for the
target, and a body that is a comment about the change
* A single annotation that has both tags and a comment about the target
* A single annotation that has a moderation up-vote, and a comment
explaining why the moderation should be considered

Motivations cannot be associated directly with the body resource, as the
body may be used in multiple annotations, with different motivations.  They
might also be the target of a different Annotation, and motivation is
exclusively tied to the Annotation that asserts it.

Therefore, a SpecificResource is needed to stand for the resource in the
context of the Annotation.
By associating the Motivation with the SpecificResource we would be clear
regarding which resource the motivation applies to.

If the Annotation and a SpecificResource both assert a motivation, the
SpecificResource's motivation would take precedence for its source
resource.

This would allow, for example:

<> a oa:Annotation ;
  oa:hasBody _:tag1sr, _:comment1sr ;
  oa:hasTarget <http://example.org/paris.jpg> .

_:tag1sr a oa:SpecificResource ;
  oa:motivatedBy oa:tagging ;
  oa:hasSource _:tag1 .

_:tag1 a oa:EmbeddedContent ;
  rdf:value "paris" .

_:comment1sr a oa:SpecificResource ;
  oa:motivatedBy oa:commenting ;
  oa:hasSource _:comment1 .

_:comment1 a oa:EmbeddedContent ;
  rdf:value "I think this is photo is of Paris because I can see the Eiffel
Tower."


Rob


-- 
Rob Sanderson
Information Standards Advocate
Digital Library Systems and Services
Stanford, CA 94305