Owen - I can answer the second. I'll have more to say on all of this but you've asked a straigthforward question which I can answer quite easily.
The current OAM draft is dated February 2013. The previous, May 2012. This current BIBFRAME draft is based on the earlier OAM draft, which used classes, and had not yet introduced the concept of motivations. At the time the February draft was released, we were just about ready to put up the BIBFRAME draft (yes, it did get delayed a couple months), and, frankly, we were not yet convinced that the motivation concept was stable, so we decided to stick with the class approach, for at least this draft, mainly to avoid destabalization. There is no technical reason why we cannot change from "class" to "motivation" in the next draft.
From: Bibliographic Framework Transition Initiative Forum [mailto:[log in to unmask]] On Behalf Of Owen Stephens
Sent: Tuesday, May 07, 2013 10:48 AM
To: [log in to unmask]
Subject: Re: [BIBFRAME] BIBFRAME annotation
My first question about Annotations in Bibframe was about whether the existing proposed uses of Annotation were 'valid' - or could be said to meet some criteria as to why they were 'annotations'.
My second is about the differences between Bibframe annotations and Open Annotation. As bf:Annotation is declared a subclass of oa:Annotation it seems that there is a desire to share a common conception of what an 'annotation' is.
The immediately obvious major difference between the way Bibframe Annotations and OA is that to specify the type of annotation Bibframe uses subclasses while OA uses the concept of 'motiviation'. I have to admit I struggle to see why Bibframe should do this differently to OA given that there is so much to gain through doing it in the same way. If there is anything to say about why bibframe proposes to do this via subclassing it would be really good to know, as the OA documentation makes it clear why they decided to go with the 'motivation' approach http://www.openannotation.org/spec/core/core.html#Motivations, and seems explicitly designed for scenarios such as the BIBFRAME one where a community has some need to specify a certain type of annotation.
In a recent email Rob Sanderson also highlighted another difference which is allowing the use of literals to carry the body of an annotation. Again the OA case for not allowing this is documented http://openannotation.org/spec/core/core.html#BodyEmbed and seems to include some use cases that seem likely to impact on the library domain - e.g. knowing directionality of text, knowing how text is encoded. Again I think some explanation of why Bibframe feels it is important to support the annotationBodyLiteral would be welcome.
In Eric Miller's recent email he noted that "Ray Denenberg (the Editor for this doc) [...] sees the compatibility and interoperability differences to be minor to negligible,". If these two differences are the major issues here, I tend to agree that there are not major differences - which, to be honest, just makes me wonder all the more why they are necessary :)