Leader (NR)
MARC 21 Classification
October 2002
Indicators and Subfield Codes
No indicators or subfield codes; the data elements are positionally defined.
Character Positions
00-04 - Record length
05 - Record status
a - Increase in encoding level
c - Corrected or revised
d - Deleted
n - New
06 - Type of record
w - Classification data
07-08 - Undefined character positions
# - Undefined
09 - Character coding scheme
# - MARC-8
a - UCS/Unicode
10 - Indicator count
2 - Number of character positions used for indicators
11 - Subfield code length
2 - Number of character positions used for a subfield code
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12-16 - Base address of data
[number] - Length of Leader and Directory
17 - Encoding level
n - Complete classification record
o - Incomplete classification record
18-19 - Undefined character positions
# - Undefined
20 - Length of the length-of-field portion
4 - Number of characters in the length-of-field portion of a Directory entry
21 - Length of the starting-character-position portion
5 - Number of characters in the starting-character-position portion of a Directory
entry
22 - Length of the implementation-defined portion
0 - Number of characters in the implementation-defined portion of a Directory entry
23 - Undefined
0 - Undefined
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FIELD DEFINITION AND SCOPE
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.
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.
GUIDELINES FOR APPLYING CONTENT DESIGNATORS
■ CHARACTER POSITIONS
00-04 - Record length Computer-generated, five-character number equal to the length of the entire
record, including itself and the record terminator. The number is right justified
and unused positions contain zeros.
05 - Record status Relationship of the record to a file for file maintenance purposes.
a - Increase in encoding level Encoding level (Leader/17) of the record has been changed from o (Incomplete
classification record) to n (Complete classification record).
c - Corrected or revised Addition/change has been made to the record. The change, however, does not
constitute an increase in the Encoding level (Leader/17) of the record.
d - Deleted Record has been deleted.
n - New Record is a newly input record.
06 - Type of record Characteristics and definitions of the components of the record.
w - Classification data Content of the record constitutes a classification record. The specific kind of
classification record is identified by the code in 008/06 (Kind of record).
07-08 - Undefined character positions Both are undefined; each contains a blank (#).
09 - Character coding scheme
a - UCS/Unicode Character coding in the record makes use of characters from the Universal Coded
Character Set (UCS) (ISO 10646), or Unicode™, an industry subset.
10 - Indicator count Computer-generated number 2 that indicates the number of character positions used
for indicators in a variable data field.
(An indicator character position contains a code which conveys information that
interprets or supplements the data found in the field.) In MARC 21, two character
positions at the beginning of each variable data field are reserved for
indicators; therefore, the Indicator count is always 2.
2 - Number of character positions used for indicators
11 - Subfield code length Computer-generated number 2 that indicates the number of character positions used
for each subfield code in a variable data field.
(Each data element in a variable data field is identified by a subfield code.) In
MARC 21, a subfield code consists of a delimiter ($) and a lowercase
alphabetic or numeric data element identifier; therefore, the Subfield code count
is always 2.
2 - Number of character positions used for a subfield code
12-16 - Base address of data 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.
Number is the base from which the starting character position of all the other
fields in the record is addressed in the Directory. (The starting character
position in the Directory entry for each field of the record is relative to the
first character of the first variable control field rather than the beginning of
the record.) The Base address of data is equal to the sum of the lengths of the
Leader and the Directory, including the field terminator character at the end of
the Directory.
[number] - Length of Leader and Directory
17 - Encoding level Indicates whether the classification record is complete or incomplete.
n - Complete classification record
o - Incomplete classification record Classification record is incomplete because it does not yet contain all the
information needed for a complete record. This character position is used for
new records that are incomplete; previously completed records in the process of
being changed are coded n in this character position and in 008/10 (Record
update in process), they are coded b (Record is being updated).
18-19 - Undefined character positions Both positions are undefined; each contains a blank (#).
20 - Length of the length-of-field portion Always a 4.
4 - Number of characters in the length-of-field portion of a Directory entry
21 - Length of the starting-character-position portion Always a 5.
5 - Number of characters in the starting-character-position portion of a Directory
entry
22 - Length of the implementation-defined portion In MARC 21, a Directory entry does not contain an implementation-defined
portion.
0 - Number of characters in the implementation-defined portion of a Directory entry
23 - Undefined
Undefined; always contains a 0.
0 - Undefined
INPUT CONVENTIONS
System-Generated Elements - The following Leader elements are usually system generated:
| 00-04 |
Logical record length |
| 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 |
| 18-19 |
Linked record requirement |
| 20-23 |
Entry map |
It is common for default values in other Leader elements to be generated automatically
as well.
Capitalization - Alphabetic codes are input as lower case letters.