> The part I'm not getting is why this thread is discussing application-specific requirements for structural constraints on data
> without reference to BIBFRAME profiles, which are _all about_ specifying structural constraints on data.

Because this thread, to my understanding, isn't about structural constraints at all, and never was. Structural constraints are an interesting topic, but as I understood Rob Sanderson's original critique, the question of "types vs. properties" isn't about constraint at all. It's about extension.

Yes, precisely.  The constraints are a distraction that came in from the discussion over whether it was a good idea to *require* inferencing or not.

Rob

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