One area where we can compare the relative expressiveness of RDA and BIBFRAME is the properties for describing relationships between resources, that is, between works, expressions, manifestations and items in terms of RDA and between works, instances and items in BIBFRAME. In RDA, these relationships are given in Appendix J (relationship designators). In BIBFRAME, they are listed in the category view in the two sections labelled Cataloging Resource Relationships – Specific and Cataloging Resource Relationships – Detailed.
I have created mappings of resource relationships from constrained RDA to BIBFRAME for each of the four resource types in RDA. They can be found on the University of Washington linked data page: http://www.lib.washington.edu/msd/pubcat/ld.
The first observation is that RDA provides a much more finely grained description of resource relationships. For example, for Works there are over 150 properties in RDA and 32 in BIBFRAME. For some types of relationships, e.g. referential relationships and whole-part relationships, the RDA-BIBFRAME mapping is one-to-one. For sequential relationships, the correspondence is close, with 22 relationships in RDA and 14 in BIBFRAME. (It was closer in BF1, but BF2 lost most of the “in part” relationships.)
For derivative relationships and accompanying relationships, however, there is a great discrepancy between the expressiveness of RDA and BIBFRAME. There are over 70 derivative work relationships in RDA but only two in BIBFRAME. For accompanying relationships, RDA has over 50 and BIBFRAME has 8.
The result is that much detail is lost when RDA concepts are expressed in BIBFRAME. RDA differentiates “abridgement of” from “graphic novelization of” from “verse adaptation of” from “digest of” from “parody of”. In BIBFRAME, we have a single choice for expressing all of these relationships: derivativeOf. RDA allows distinctions between addenda, appendices, concordances and errata but in BIBFRAME they must be rendered identically as accompaniedBy.
My second observation is that BIBFRAME’s treatment of resource relationships does not support the user experience we hope to provide under RDA. The elaboration of resource relationships is one of the significant advances that RDA has made over AACR2. When catalogers invest intellectual effort to determine resource relationships, this information should be displayed to users in our library catalogs. BIBFRAME-encoded cataloging does not fully allow us to do so.