Character position definition and scope:

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.

More detailed information about the structure of the Directory entries is contained in MARC 21 Specifications for Record Structure, Character Sets, and Exchange Media.

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

National level record requirement for the Directory and all 12 character positions is Mandatory.

The Directory is NOT repeatable.

Description of a Directory entry:

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





See example




Data elements:




00 - 02




03 - 06

Field length



07 - 11

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 corresponding 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:

LC Guidelines:


Related MARC fields or documents:

Leader/20-23  Entry map

MARC 21 Specifications for Record Structure, Character Sets, and Exchange Media

See also:

MARC 21 Format for Authority Data:  Contents