Leader (Classification)

Field definition and scope:

The Leader is the first field of a classification record. It is fixed in length at 24 character positions (00-23). The Leader consists of data elements that contain numbers or coded values that define the parameters for the processing of the record. Alphabetic codes are entered in lowercase.

Character positions 20-23 comprise the Entry map for the Directory. They contain four one-character numbers that specify the structure of the entries in the Directory. More detailed information about the structure of the Leader is contained in MARC 21 Specifications for Record Structure, Character Sets, and Exchange Media.

The Leader is NOT repeatable.

Guidelines for applying content designators:

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

The table below includes all 24 character positions of the Leader in classification records. Positions are conventionally numbered zero (0) through 23. For details on Leader character positions and codes, select a topic:

Position	Description
00-23	Leader
Data elements:
00-04	Record length
05	Record status
06	Type of record
07-08	Undefined character positions
09	Character coding scheme
10	Indicator count
11	Subfield code count
12-16	Base address of data
17	Encoding level
18-19	Undefined character positions
20-23	Entry map

Input conventions:

System-generated elements

Capitalization