All, We're thinking about modeling identifiers (and other properties?) in two ways: 1) generic property with a more specific data type: bf:identifer "9780394856308"^^http://example/org/isbn13 or 2) specific property: bf:isbn13 "9780394856308" where 'bf:isbn' is a subproperty of 'bf:identifier'. How does the community feel about these two options, and why? Thanks, Nate ------------------------------------------- Nate Trail ------------------------------------------- LS/TECH/NDMSO Library of Congress 202-707-2193 [log in to unmask]<mailto:[log in to unmask]>