On Sun, Nov 9, 2014 at 7:44 AM, [log in to unmask] <[log in to unmask]>

> On Nov 7, 2014, at 7:13 PM, Thomas Baker <[log in to unmask]> wrote:
> > I'm not following... Coining lots of new classes provides a simple way
> of extending the vocabulary?
> I don't want to put words in Rob Sanderson's mouth (since he made the
> original critique) but I do agree with him, so I'll offer my point of view:
> it's a question of whether it is easier to extend the vocabulary by adding
> new predicates, or by adding new types.

Happy to have those words put in my mouth :)

> That is, "simple" is relative to the choices. This is especially so if the
> Bibframe predicate vocabulary remains committed to the particular Bibframe
> "two-level" model.

However I'll object to the two level characterization on the following

1.  It's at least three level with Work, Instance and HeldItem.

2.  It's really the four level FRBR model, given the bf:expressionOf
predicate, just that *cough* you have to infer that the subject of that
predicate is an Expression-y type of Work, rather than a Work-y type of

Yes, I would prefer to have bf:Expression as a class and be done with it,
or to get rid of the FRBR work around predicates (expressionOf and


Rob Sanderson
Technology Collaboration Facilitator
Digital Library Systems and Services
Stanford, CA 94305