Repeatability of fields and subfields:
The MARC guidelines for each field and subfield indicate whether a field can be repeated within the same record or a subfield repeated within the same field.
Theoretically, all fields and subfields may be repeated. The nature of the data in a field, however, often precludes repetition. The repeatability or nonrepeatability of each field and subfield is specified.
Field and subfield repeatability/nonrepeatability is sometimes indicated in written and on-line MARC documentation by the abbreviations R or NR following the description of each field and subfield in the appropriate MARC format.
See also: