Skip to main content
OCLC Support

Directory

  1. Last updated
  2. Save as PDF
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