You can find the background for this decision in the Subject Headings Manual, H 364. It says,
The Library's past practice was to authorize subject headings for geographic subdivision only when further subdivision by place was actually needed for works being cataloged. Currently, new headings are authorized for geographic subdivision at the point when they are established if they represent topics that could exist in a specific location or could be discussed in relation to a place, whether or not geographic subdivision is needed for the item in hand.
Hope this helps!
Social Sciences and Map Catalog Librarian
UCLA Library Cataloging & Metadata Center
11020 Kinross Ave.
Los Angeles, CA 90095-7230
From: Program for Cooperative Cataloging [mailto:[log in to unmask]]
On Behalf Of Jesse Lambertson
Sent: Friday, March 10, 2017 8:29 AM
To: [log in to unmask]
Subject: (may subdivide geographically) ?
I am looking at the Subjects Headings manual for information, a complete rule, on when a topic may be geographically subdivided and when it may not.
Cataloger's Desktop lists all the headings and includes the additional note about which ones may be subdivided geographically. It also mentions the addition of (May Subd Geog) as generated from the existence of "i" in field 008/06 in the authority record.
But I am looking for the rule that actually explains why some headings can be while others not.
In which documentation might I find this philosophical guidance?