On the NGC4Lib listserv, Neil Godfrey writes, and I respond:
Apols if I have missed any previous explanation of this, but I am wondering what reason/s lie behind RDA continuing the concept of “a preferred acces point” in cases of multiple authors for a work.
Is the reason primarily to accommodate the contingencies of MARC-based cataloguing? Are there other reasons such as data exchange and identification or other?
What difference/s does “a preferred access point” make in online databases and user interfaces?
This is just my interpretation….
I think “preferred access point” is a really bad choice of term. What they should have called this is “Citation Heading” or something like that, something involving the word “citation” or perhaps “reference”.
It’s purpose is so you can “cite” or “reference” a different record in (for example) a 700 name-title. In order to do that traditionally, you would use the “main entry” heading. You need to be able to put a certain string in that field that can unambiguously identify a referenced/cited record. This is the purpose of the “preferred access point”, and the only purpose I can see.
You could think of it almost like a modern “foreign key” to relate one record to another.
Now, in 2010, the _better_ way to do this kind of “citation” or “reference” is with an actual controlled identifier (an accession number, a URI, etc). (You know, more like the way “foreign keys” actually work).
I wish that RDA made it clear that this is _preferable_, and allowed you to use _only_ an identifier when available. I am not sure if it does. But even if it did, I think it is a good idea to — as our legacy practices always have — allow this kind of reference/citation using a controlled “heading” instead of an actual modern identifier, for backwards compatibility purposes if nothing else, but I’m not sure it doesn’t have other utility as well.