20.0 Assigning subject and form headings

21.0 Depth (levels) of subject cataloging

22.0 Specific (co-extensive) entry

23.0 Headings authorized for use in subject cataloging

24.0 Assignment of main headings

25.0 Use of subdivisions

26.0 Number of headings

27.0 Partial title added entries

28.0 Works on new topics

See also:

Policies for Assigning Subject Headings