It might be best to ask on the OCLC-CAT list; several people from their QC section are active participants and answer questions.
My first thought was that the 019 shows several other OCLC control numbers, so these could have been retained from other duplicate records created in batch processes, like loads from vendor or library catalogs. My understanding is that OCLC’s algorithms retain any distinctive SH schema. The FAST headings would have been added intentionally by OCLC in another automated process. Searching the ISBN shows several more duplicate records in OCLC which may also be merged eventually. If any of these have unique SH they’ll be retained too. I guess the principle is that is easier for other libraries to delete them or exclude them from indexing than it is to add them locally. I am unaware of any libraries that actually use BISACSH, but I know there was trend in public libraries to adopt bookstore categories for shelving and signage so they may be useful for that. I can’t think of a reason anyone would want 650_4’s identical to the 650_0’s, on the other hand.
Coordinator, Cataloging Services
261B Bierce Library
The University of Akron
Akron, Ohio 44325-1712
From: Program for Cooperative Cataloging <[log in to unmask]>
On Behalf Of Yang Wang
Sent: Thursday, March 28, 2019 2:36 PM
To: [log in to unmask]
Subject: [PCCLIST] Evolution of a master record in OCLC
I was doing a set of subject heading corrections with regard to “Civil rights movements” (lcsh) vs “Civil rights movement” (series title) in the local database and found in the following bib record a plethora of “extras” in 6XX. The record was originally created and authenticated by LC (https://lccn.loc.gov/2016044049, a BSR par excellence!); now the 6XX have greatly expanded (OCoLC)ocn966314870).
My question is: Why is this type of expansion/additions even allowed on a master record? More user friendly?