Marc 21 Record Format -- Leader Section

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MARC21 ::= Leader + Record Directory + Variable Fields + X'1B'

Leader ::= Leader1 + Leader2 + Leader3 + Leader4 + Leader5 -- char(24)
Leader1 ::= Logical Record Length + Record Status + Record Type
Leader2 ::= Bibiographic Level + Type of Control + Character Coding Scheme
Leader3 ::= Indicator Count + Subfield Code Count + Base Address of Data
Leader4 ::= Encoding Level + Descriptive Catalog Form + Linked Record Requirement
Leader5 ::= Entry Map

Logical Record Length ::= '99999' -- char(5)

Logical record length, right justified, zero padded

Record Status ::= 'A' | 'C' | 'D' | 'N' | 'P' -- char(1)

Indicates the relation of the record to a file.

Record Type ::= 'A' | 'C' | 'D' | 'E' | 'F' | 'G' | 'I' | 'J' | 'K' | 'M' | 'O' | 'P' | 'R' | 'T' -- char(1)

Indicates the characteristics of and defines the components of the record.

Bibiographic Level ::= 'A' | 'B' | 'C' | 'D' | 'M' | 'S' -- char(1)

Type of Control ::= ' ' | 'A' -- char(1)

Archival or no specific type.

Character Coding Scheme ::= ' ' | 'A' -- char(1)

one-character code that identifies the character coding scheme used in the record. 'A' equals UCS/Unicode, otherwise MARC-8.

Indicator Count ::= '2' -- char(1)

Columns used for indicators, always 2

Subfield Code Count ::= '2' -- char(2)

columns used for subfield codes, always 2

Base Address of Data ::= '99999' -- char(5), right justified, zero padded

indicates the first character position of the first variable control field in a record.

Encoding Level ::= ' ' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | 'U' | 'Z' -- char(1)

Indicates the fullness of the bibliographic information and/or content designation of the MARC record.

Descriptive Catalog Form ::= ' ' | 'A' | 'I' | 'U' -- char(1)

Indicates the descriptive cataloging form reflected in the record. Subfield e (Description conventions) of field 040 (Cataloging Source) may contain additional information on the cataloging conventions used.
' ' - Non-ISBD -- The descriptive portion of the record does not follow International Standard Bibliographic Description (ISBD) cataloging and punctuation provisions.
'A' - AACR 2 -- The descriptive portion of the record and the choice and form of entry of the access points are formulated according to either the second edition of the Anglo-American Cataloguing Rules or cataloging manuals based on AACR 2. The punctuation practices of ISBD apply.
'I' - ISBD -- The descriptive portion of the record is formulated according to the descriptive and punctuation provisions of ISBD. The heading forms are not formulated according to AACR 2. This category includes records that use ISBD punctuation but the other conventions used are unknown.
'U' - Unknown -- An organization receiving or sending data in Leader/18 cannot determine the appropriate descriptive cataloging form used in the record. Code u is not used in newly input or updated records.

Linked Record Requirement ::= ' ' | 'R' -- char(1)

A one-character code that indicates whether a note containing basic identification information (i.e., main entry and title, main entry and uniform title, main entry under uniform title, title, uniform title, Standard Technical Report Number, or report number) can be generated from a Linking Entry field (76X-78X).

Entry Map ::= '4500' -- char(4)

Four computer-generated, single-digit numeric characters that indicate the structure of each entry in the Directory.