The Directory is an index to the location of data within a record, consisting of a series of fixed-length entries, with one entry for each variable field (control or data) present in a record.  Each Directory entry is 12 character positions in length, starting with position zero (0) and ending with position 11.  Each entry contains three portions, detailed below:  the field tag, the field length, and the starting character position.  The Directory immediately follows the Leader at the beginning of the record and is located at character position 24.

The Field length and Starting character position portions of the Directory are defined by Leader/20-23 (Entry Map) as being 4 and 5 characters in length, respectively.  Because a field tag is always 3 characters, the length of the Tag portion of the Directory is not specified in the Entry map.

Users typically do not have access to the Directory.  Each Directory entry is generated automatically by the system.

National and minimal level record requirements for the Directory for all formats are Mandatory.

Description of a Directory entry:

The Directory has no indicators or subfield codes.  The data elements are positionally defined.






Field length


Starting character position

Order of entries:

Directory entries for variable control fields appear first, sequenced by tag in increasing numerical order.  Entries for variable data fields follow, arranged in ascending order according to the first character of the tag.  The stored sequence of the variable data fields in a record does not necessarily correspond to the order of the Directory entries.  Duplicate tags are distinguished only by the location of their respective fields within the record.  The Directory ends with a field terminator character (ASCII 1E hex).

MARC Authority, Bibliographic, Classification, Community Information, and Holdings format records all have identical directory structures.

Example of a Directory:

For information about the Directory in a specific MARC format, select:

Directory  (Authority)

Directory  (Bibliographic)

Directory  (Classification)

Directory  (Community Information)

Directory  (Holdings)

For return, select:

Elements of a MARC Record

Components of a MARC Record

A General Introduction to the MARC Format