There are 5 categories of free

There are 5 categories of free-floating subdivisions. The most commonly used of these is the "Form and Topical Subdivisions of General Application." These general subdivisions are listed alphabetically with brief guidelines that describe how and when to use each subdivision. These can be used under most of the topics listed in LCSH. Here are some examples taken from Free-Floating Subdivisions: An Alphabetical Index, 13th edition (Washington, D.C.: Library of Congress Cataloging Distribution Service, 2001):

SUBDIVISION	SUBFIELD CODE(S)	FREE-FLOATING LIST IN SCM:SH	CATEGORY	USAGE GUIDELINES IN SCM:SH
-Slides	v	H 1095 H1110 H1140	see SCM:SH Indiv pers Families
-Social aspects (May Subd Geog)	x	H 1095 H1153 H1154 H1200	see SCM:SH Industries Languages Wars
-Societies, etc.	x	H 1095 H1100 H1103 H1105 H1110 H1188	see SCM:SH Classes pers Ethnic groups Corp bodies Indiv pers Sacred works	H2060 H2060 H2060 H2060 H2060 H2060
-Sociological aspects	x	H 1095 H1151.1	see SCM:SH Types schools	H2055
-Software	v	H1095	see SCM:SH	H2055
-Songs and music	v	H 1095 H1100 H1103 H1105 H1110 H1140 H1159	see SCM:SH Classes pers Ethnic groups Corp bodies Indiv pers Places Military srvces

The first column lists the valid subdivision term. The second column indicates the type of subdivision, using USMARC subfield codes. An "x" is a topical subdivision; a "v" is a form subdivision. Although there are no examples in the above list, a "y" would indicate a chronological subdivision, and a "z" a geographical subdivision.

The third column indicates the section of subdivisions in the Subject Cataloging Manual: Subject Headings in which this subdivision appears. A fuller explanation of how this subdivision is to be used appears in this section. The fourth column gives a description (in abbreviated form) of possible categories of subject headings for which this subdivision can be used. For example, if the library owns some slides of an individual, and you want to make a subject heading indicating this, you will need to look in H1110 in the Subject Cataloging Manual: Subject Headings for basic notes on how to do this. The fifth column shows where more detailed usage guidelines and examples of USMARC formatting using this subdivision can be found in the Subject Cataloging Manual: Subject Headings. These will be further addressed in the course on MARC cataloging.