In my previous post, I talked about the three database scenarios proposed by the JSC for RDA. These can be considered to be somewhat schematic because, of course, real databases are often modified for purposes of efficiency in searching and display, as well as to facilitate update. But the conceptual structures provided in the JSC document are useful ways to think about our data future.
There is one problem that I see, however, and that is the transition from authority control to entities. Because we have authority records for some of the same things that are entities in the entity-relationship model of FRBR, there seems to be a wide-spread assumption that an authority record is the same as an entity record. In fact, IFLA has developed "authority data" models for names and for subjects that are intended to somehow mix with the FRBR model to create a more complete view of the bibliographic description.
This may be a wholly mis-guided activity, for the reason that authority control and entities (in the entity-relation sense) are not at all the same thing.
The library authority control, and the record that carries the information, has as its sole purpose to provide the preferred heading representing the "thing" being identified (person, corporate body, subject heading). It also provides non-preferred forms of the name or subject that might be ones that a catalog user would include in a query for that thing. The rest of the information contained in the record is solely in support of the process of selection of the appropriate string, including documentation of the resources used by the cataloger in making that decision. In knowledge organization thinking, this would be considered a controlled list of terms.
To understand what an entity is, one might use the WEMI entities as examples. An entity is indeed about some defined "thing," and it contains a description of that thing that fulfills one or more intended uses of the metadata. In the WEMI case, we can cite the four FRBR user tasks of find, identify, select, obtain. So if Work is an entity and contains all of the relevant bibliographic information about that Work, then Person is an entity and should contain all of the relevant information about that person. One such piece of information could be a preferred form of the person's name for display in a particular community's bibliographic data, although I could also make the argument that library applications could continue to make use of brief records that support cataloging and display of controlled text strings if that is the only function that is required. In fact, in the VIAF union database of authority data, the data is treated as a controlled list of terms, not unlike a list of terms for languages or musical instruments.
What would be a Person entity? It could, of course, be as much or as little as you would like, but it would be a description of the Person for your purposes. It is this element of description that I think is key, and we could think of it in terms of the FRBR user tasks:
find - would help users find the Person using any form of the name, but also using other criteria like: 19th century French generals; Swedish mystery writers; translators of the Aeneid.
identify - would give users information to help disambiguate between Persons retrieved. This assumes that there would be some amount of biographical information as well as categorization that let users know who precisely this Person entity represents.
select - this is where this would differ from traditional FRBR which seems to assume that one is already looking for bibliographic materials at this step. I suppose that here one might select between Charles Dodgson and Lewis Carroll, whose biographic information is similar but whose area of activity is entirely different.
obtain - this step would lead one to the library's held works by and/or about that Person, but it could also lead to further information, like web pages, entries in an online database, etc.
If you are wondering what a Person entity might look like, it might look like a mashup between an entry in WorldCat identities and Wikipedia. I suggest a mashup because Identities is limited to data already in bibliographic and authority records and therefore has little in the way of general biographical information. That latter is available, sometimes abundantly, in Wikipedia, and of course a link to that Wikipedia entry would be a logical addition to a library record for a Person entity.
What this thinking leads me to conclude is:
1) the library authority file is a term list, not a set of entities, and therefore is not the Person entity implied in FRBR
2) having person entities in our files could be a great service for our users, and it might be possible to create them to take the place of the simple term lists that our authority records now represent
3) the FRBR user tasks may need to be modified or reinterpreted to be focused less on seeking a particular document and more on seeking a particular person (agent) or subject