A separate portion of data elements in a field in a bibliographic record The order of the subfields is determined by the field in which they are assigned
The smallest logical unit of information in a variable field Subfield codes (letters or numbers) identify subfields and are preceded by subfield delimiters () Subfield a is implicit at the beginning of each field, but does not appear
A subdivision of a variable field containing data logically identifiable as a discrete unit of that field A typical publication field, for example, has three subfields: place, publisher, and date Except for subfield "a" at the beginning of a field, each subfield is proceeded by a delimiter ( ‡ ) and a subfield code
A part of a datum for which the representation is described by a simple (not compound) representation code For example, the subfields of a datum having representation code OBNAME are origin (ORIGIN), copy (UVARI), and identifier (IDENT)