MARC 21 Concise Classification: Leader and Directory

This is an ARCHIVED VERSION of the 2002 electronic edition of the MARC 21 Concise Formats. Please see www.loc.gov/marc/concise/ for the most up-to-date version of the electronic MARC 21 Concise Formats.

• LEADER
• DIRECTORY

Information for Translators and Other Users
Items highlighted in red indicate changes made after the 2001 edition of the MARC 21 Concise Formats was published and are included in the 2002 printed edition of the MARC 21 Concise Formats.

LEADER

A fixed field that comprises the first 24 character positions (00-23) of each record and provides information for the processing of the record.

Character Positions

• 00-04 - Record length
  The computer-generated, five-character numeric string that specifies the length of the entire record. The number is right justified and each unused position contains a zero.
• 05 - Record status
  Indicates the relation of the record to a file.
  • a - Increase in encoding level
  • c - Corrected or revised
  • d - Deleted
  • n - New
• 06 - Type of record
  Indicates the characteristics of and defines the components of the record.
  • w - Classification data
• 07-08 - Undefined character positions
  Each contains a blank (#)
• 09 - Character coding scheme
  • # - MARC 8
  • a - UCS/Unicode
• 10 - Indicator count
  The computer-generated number 2 that indicates the number of character positions used for indicators in a variable data field.
• 11 - Subfield code length
  The computer-generated number 2 that indicates the number of character positions used for each subfield code in a variable data field.
• 12-16 - Base address of data
  The computer-generated, five-character numeric string that indicates the first character position of the first variable control field in a record. The number is right justified and each unused position contains a zero.
• 17 - Encoding level
  Indicates whether the record is complete.
  • n - Complete classification record
  • o - Incomplete classification record
• 18-19 - Undefined character positions
  Each contains a blank (#)
• 20-23 - Entry map
  Four computer-generated, single-digit numeric characters that indicate the structure of each entry in the Directory.
• 20 - Length of the length-of-field portion
  Contains a 4
• 21 - Length of the starting-character-position portion
  Contains a 5
• 22 - Length of the implementation-defined portion
  Contains a 0
• 23 - Undefined
  Contains a 0

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DIRECTORY

A computer-generated index to the location of the variable control and data fields within a record. The Directory immediately follows the Leader at character position 24 and consists of a series of fixed-length (12 character positions) entries that give the tag, length, and starting character position of each variable field.

Character Positions

• 00-02 - Tag
  Three numeric or alphabetic (uppercase or lowercase, but not both) characters that identify an associated field.
• 03-06 - Field length
  Four numeric characters that indicate the length of the field, including indicators, subfield codes, data, and the field terminator. The number is right justified and each unused position contains a zero.
• 07-11 - Starting character position
  Five numeric characters that indicate the starting character position of the field relative to the Base address of data (Leader/12-16) of the record. The number is right justified and each unused position contains a zero.

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