"Every record in PsycINFO® databases receives a classification code, which is used to categorize the document according to the primary subject matter. These classification codes can help you target your search by allowing you to restrict retrieval to a specific category. There are 22 major categories and 135 subcategories, and a list of codes. Each record is assigned to one or two classifications.
NOTE: This classification code system was designed to describe the content of the PsycINFO database, not the field of psychology."