Introduction and Specifications

MARC 21 is a widely used standard for the representation and exchange of data and information in the library sector in machine-readable format. MARC was initially developed in 1969 by the Library of Congress and lived through several versions until MARC 21 became the standard format for bibliographic records worldwide. Maintenance and development of the MARC standards is the responsibility of the Network Development and MARC Standards Office, supported by the MARC Advisory Committee.

MARC 21 offers five communication formats:

The Format for Bibliographic Data is designed to be a carrier for bibliographic information about: printed and manuscript textual materials, computer files, maps, music, continuing resources, visual materials, and mixed materials.

A MARC 21 record consists of three main components: the Leader, the Directory, and the Variable fields.

  • Leader: This is the first field of a MARC record and provides information for the processing of the record. The length of the leader is fixed on 24 characters.
  • Directory: A series of entries that contain the tag, length, and starting location of each variable field within a record. Each entry is 12 character positions in length. Directory entries for variable control fields appear first, sequenced by the field tag in increasing numerical order. Entries for variable data fields follow, arranged in ascending order according to the first character of the tag.
  • Variable fields: The actual data is organized in variable fields. They can be identified through a three-character-numeric tag that points to a specific kind of information provided by the standard. There are two types of variable fields: The control fields and the data fields:
    • Control fields (00X): They usually occur at the beginning of a record and either contain a single data element or a series of fixed length data elements. They do not contain indicator positions or subfield codes.
    • Data fields: In addition to the field tag they contain two indicator positions and a subfield code for each data element in the field to describe its specifics. The first character of the field tag points to the function of the data.

Field TagFunction of Data
0XXControl information, identification and classification numbers, etc.
1XXMain entries
2XXTitles and title paragraph (title, edition, imprint)
3XXPhysical description, etc.
4XXSeries statements
6XXSubject access fields
7XXAdded entries other than subject or series; linking fields
8XXSeries added entries, holdings, etc.
9XXReserved for local implementation
Different groups of field tags (Source:

Example of a Variable datafield with four different subfields (a=name, d=biographic information, 0=identifier, 4=role):

<datafield tag="100" ind1="1" ind2=" ">
<subfield code="a">Lorenz, Konrad</subfield>
<subfield code="d">1903-1989</subfield>
<subfield code="0">(DE-588)118574337</subfield>
<subfield code="4">aut</subfield>

Additional Material

Mandatory Fields for Europeana

If you plan to submit MARC 21 metadata to Europeana you need to include these mandatory fields:

(1) 856$u (6) 245$a; 242; 240
(2) 542$u(7) 001; 020; 022$a; 035$a
(3) 535$a; 852$a (8) 041$a
(4) 857$b; 858$b(9) 007, first letter
(5) 300$b; 337$a

Recommended Fields for Europeana

We recommend that you fill in as many data fields as possible so that your dataset is easier to understand for a wide audience and the public. It is also much easier to link a well-described dataset to other data in the shared portal. Here are some more data fields that we particularly suggest you use.

(1) 700; 710; 711 (6) 245$a
(2) 260$c, 264$c (7) 650$a; 653$a
(3) 300$a; 300$c (8) 650$z; 651$a; 662
(4) 260$a$b, 264$b (9) 648
(5) 100; 110; 111