About record structure
"Record Structure" describes the general structure for the leader, the directory, and the control and variable fields in OCLC-MARC bibliographic and authority records.
OCLC-MARC format
OCLC-MARC formats are sets of codes and content designators defined for encoding particular types of machine-readable records. They serve as the vehicle for bibliographic and authority data for all types. The formats provide specifications for the exchange of information between systems.
Additional information on OCLC-MARC format
For descriptions of the OCLC-MARC bibliographic and authority records, see Bibliographic Formats and Standards and Authorities: Format and indexes.
Content designation
Content designation identifies and characterizes the data elements that comprise OCLC-MARC records.
Tags and fields
- OCLC-MARC records are organized into fields identified by three-character numeric tags
- The tag is stored in the directory entry for the field, not the field itself
- Fields are grouped into blocks according to the first character of the tag, which generally identifies the function of the data in the record
- The type of block varies with each type of record: bibliographic or authority
Bibliographic record blocks
Bibliographic records have the following blocks:
- 0xx Control information, numbers, and codes 1xx Main entry
- 2xx Titles and title paragraph 3xx Physical description, etc. 4xx Series statements
- 5xx Notes
- 6xx Subject access fields
- 7xx Added entries other than subject or series; linking fields 8xx Series added entries, location, and alternate graphics 9xx OCLC-defined local fields
Authority record blocks
Authority records have the following blocks:
- 0xx Control information, numbers, and codes 1xx Heading
- 2xx Complex see references
- 3xx Complex see also references
- 4xx See from tracings
- 5xx See also from tracings
- 6xx Reference notes, treatment decisions, notes, etc.
- 7xx Heading linking entries
- 8xx Location and alternate characters
- 9xx OCLC-defined local fields
Repetibilidad
- All fields are theoretically repeatable
- The nature of the data in the fields, however, may preclude repetition
- Examples of nonrepeatable fields include 001 (Control Number), 005 (Data and Time of Latest Transaction), and field 245 (Title Statement)
- OCLC-MARC Records specifies the repeatability (R) or nonrepeatability (NR) of each field and subfield in the lists of content designators
Coded data
- OCLC-MARC formats include specifications for data elements represented by coded values
- Coded values consist of fixed-length character strings
- Elements within coded-data fields or subfields may be identified by relative character position
- Although coded data occurs most frequently in the leader, directory, and variable control fields, any field or subfield may be defined for coded data