OCLC local holdings records (LHRs) are separate holdings records attached to a related WorldCat bibliographic record that provide holdings details beyond your OCLC institution symbol.
The OCLC local holdings record structure is based on the MARC 21 Format for Holdings Data and consists of three main components: the Leader, the Directory, and the Variable Fields.
Contains data elements that provide information for the processing of the record. The data elements contain numbers or coded values and are identified by a relative character position. The Leader is fixed in length at 24 character positions and is the first field in all MARC records.
Contains a series of entries that contain the tag, length, and starting location of each variable field within a record. The directory is not visible to users through Connexion.
The data in a MARC 21 record is organized into variable fields, each identified by a three-character numeric tag that is stored in the Directory entry for the field. Each field ends with a field terminator character. The MARC record ends with a record terminator (ASCII 1D hex). There are two types of variable fields:
- Variable control fields: The tagged 007 and 008 fields are defined in OCLC local holdings records. The variable control fields are structurally different from the variable data fields. These fields contain neither indicator positions nor subfield codes. They contain a series of fixed-length data elements identified by relative character position.
- Variable data fields: The tagged 02X, 035, 5XX, and 8XX fields are used in OCLC local holdings records. These fields are variable in length and number. MARC variable fields have three parts:
- A three-digit tag
- Two single-digit indicators
- One or more subfields
MARC tags identify variable fields and are grouped numerically by function.
|0xx||Bibliographic control numbers and coded information|
|3xx||Information about presentation medium and format of the bibliographic item|
|8xx||Notes, location, and holdings data|
In the MARC records, indicators supply information about the field for indexing, card production, or other system functions. Numbers in the indicator positions have assigned meanings and in some fields, a blank space is meaningful. Variable field indicators may have:
- A number in both positions
- A number in one position and a blank space in the other
- Two blank spaces
Subfields are the smallest logical unit of information in a variable field. Subfield codes (letters or numbers) identify subfields and are preceded by a subfield delimiter (‡).
Subfields may contain either coded or textual information. In OCLC Connexion, subfield ‡a is implicit at the beginning of each field and does not display.