When assigning subject headings, you often have to construct strings consisting of a main heading and one or more subheadings. How to arrange them can be confusing, but here is a general rule:
[Main heading] – [general subheading] – [geographic subheading] – [Period subdivision] -- [Format related subheading].
Examples: Geology – Research – Utah.
Geology – Utah – Salt Lake County – Maps.
Utah -- History -- 19th century.
The LC authorities website has numerous examples of subject heading strings, but keep in mind that it is not intended to be comprehensive; it was compiled from subjects that have actually been used by OCLC catalogers.
There are many “free-floating subheadings” that can be applied to many different main headings. Here is a list of commonly used subheadings:
Here are some subheadings particularly useful for works about individuals and the course of their lives, as well as for their own works and other things connected to them: