Directory
Find the structure and elements for the record directory in OCLC MARC records.
The record directory consists of a series of fixed-length entries containing the tag, length, and starting character position of each control and variable field in the record. A field terminator ends the record directory. Each entry is 12 bytes.
Directory structure
The following diagram illustrates the structure of a directory entry:
00-02 |
03-06 |
07-11 |
Tag |
Field Length |
Starting Character Position |
Directory elements
Each variable field in bibliographic and authority records has the following elements:
Element |
Description |
Tag |
- Positions 00-02
- Three-character number that identifies an associated variable field
|
Field Length |
- Positions 03-06
- Four-character number that specifies the length of the variable field to which the entry corresponds
- Equal to the sum of the length of the indicators, subfield codes, data, and the field terminator associated with the field
- If fewer than four digits, right justified with leading zeros
|
Starting Character Position |
- Positions 07-11
- Five-character number that specifies the starting character position of the variable field to which the entry corresponds relative to the base address of the data of the record
- If fewer than five digits, right justified with leading zeros
|