Directory (NR)
MARC 21 Classification
January 2000
Indicators and Subfield Codes
No indicators or subfield codes; the data elements are positionally defined.
| Character Positions 00-02 - Tag
03-06 - Field length
07-11 - Starting character position |
CHARACTER POSITION DEFINITION AND SCOPE
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 and
contains three portions: 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
the MARC 21 Specifications
for Record Structure, Character Sets, and Exchange Media.
DESCRIPTION OF A DIRECTORY ENTRY
■ CHARACTER POSITIONS
00-02 - Tag Three ASCII numeric or ASCII alphabetic characters (upper case or lower case, but
not both) that identify an associated variable field.
03-06 - Field length Four ASCII numeric characters that specify the length of the variable field
including indicators, subfield codes, data, and the field terminator. A Field
length number of less than four digits is right justified and unused positions
contain zeros.
07-11 - Starting character position Five ASCII numeric characters that specify the starting character position of the
variable field relative to the Base address of data (Leader/12-16) of the record.
A Starting character position number of less than five digits is right justified
and unused positions contain zeros.
■ EXAMPLE
| |
Tag |
Field length |
Starting character position |
| Entry 1 |
001 |
0013 |
00000 |
| Entry 2 |
005 |
0016 |
00013 |
| Entry 3 |
008 |
0015 |
00029 |
| Entry 4 |
153 |
0040 |
00044 |
INPUT CONVENTIONS
System-Generated Elements - Each Directory entry is system generated.