Content Designators Content Designators Within variable data fields , two kinds of content designators are used to interpret, supplement, or delineate the data found in the field. They are indicator positions and subfield codes . Indicators and subfield codes are not used in variable control fields .
Indicators contain values which interpret or supplement the data found in the field.
Indicator values are interpreted independently, that is, meaning is not ascribed to the two indicators taken together. Indicator values may be a lowercase alphabetic or a numeric character. In a defined indicator position, a blank may be assigned a meaning, or may mean No information provided . Subfield codes are two characters that precede each data element within a field that requires separate manipulation. The data element identifier may be a lowercase alphabetic or a numeric character.