X00 Subfield $v - Form subdivision:

Subfield $v contains a form subdivision that designates a specific kind or genre of material as defined by the thesaurus being used. Subfield $v is appropriate only when a form subject subdivision is added to a personal name heading to form an extended subject heading . Subfield $v is used for form terms when they function as indicated above; the terms are coded in subfield $x if they function as general subdivisions.

Examples:

100 0#$aGautama Buddha$vBiography$vEarly works to 1800

100 3#$aClark family$vFiction