A thesaurus describes the semantic rules that govern the meaning of words in a MARC record. The thesaurus code, which indicates the specific thesaurus that should control a MARC record, is encoded in a fixed field using the mnemonic Subj in the authority record. Eleven thesauri associated with the Library of Congress control set exist by default in the staff client.
To access an existing thesaurus, click Administration → Server Administration → Authority Control Sets, and choose the hyperlinked thesaurus that you want to access, or click Administration → Server Administration → Authority Thesauri.