Directory

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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