01. Introduction

What is the CBS MARC 21 format?

The CBS MARC 21 format is called so, because it is a combination or synthesis of:

• MARC 21 fields
  • The MARC 21 fields of the (Library of Congress) MARC 21 format. We have implemented the bibliographic, holdings and authority format. This forms the core of the CBS MARC 21 format.
  • The additional OCLC MARC 21 fields. I.e. the fields defined by OCLC, especially for WorldCat. By OCLC several fields on the main level, but mainly on the local level have been added to the "official" MARC 21 format. This is called WorldCat MARC 21.
  • MARC 21 extensions to, i.e. these are not part of the Library of Congress and the OCLC, Dublin (WorldCat) format. These tags can be applied within the context of a CBS MARC 21 database only. "Extension" means that certain MARC 21 fields can be used on another level too. E.g. the field 500 has been defined only on main level in the "official" MARC 21 format. But in a CBS MARC 21 database, this field can also be used on copy/LHR level.
• CBS system and non-system fields
  • CBS fields. These are non-(OCLC) MARC 21 fields. CBS fields are defined by OCLC, Leiden.

When the OCLC MARC 21 (OCLC, Dublin) format has certain limitations in comparison with the Library of Congress MARC 21 format, i.e. that certain tags, subfields or values are not allowed in the OCLC (WorldCat) MARC 21 format, the Library of Congress MARC 21 format is primarily! It implies that the CBS MARC 21 (OCLC, Leiden) format contains all MARC 21 tags in principle.

Levels in bibliographic records

We use the term bibliographic records. We distinguish three levels in bibliographic records:

• Main/master level
• Local level, also called LBD, i.e. Local Bibliographic Data
• Copy level, also called LHR, i.e. Local Holdings Record

Additional documentation

In this part of the documentation of the CBS MARC 21 format, the fields of the CBS MARC 21 cataloguing format of bibliographic and holdings records are described on tag level only; no indicators and subfields are mentioned. Also the PICA+ fields related to the CBS MARC 21 tags are mentioned.

The documentation about the (OCLC) MARC 21 tags can be found on the websites of the Library of Congress and OCLC. E.g. the indicator values, the allowed subfields and their meaning, examples etc. We have added links to the MARC 21 documentation of the Library of Congress and OCLC, Dublin.

But for the next fields, separate documentation exists, because these elements have been divided into subfields within the structure of the CBS MARC 21 format:

• Leaders - bibliographic and holdings format. For more details, see: ... (under construction).
• Fields 006 Fixed-Length Data Elements – Additional Material Characteristics - bibliographic format. For more details, see: ... (under construction).
• Fields 007 Physical Description Fixed Field - bibliographic and holdings format. For more details, see: ... (under construction).
• Fields 008 Fixed-Length Data Elements - bibliographic and holdings format. For more details, see: ... (under construction).

Structure of tables

Next pages contain tables per tag range. How must these tables be read?

• Cells marked with yellow are defined in the CBS MARC 21 format. These tags are "active", i.e. they can be used. So, tags marked with yellow are defined in the CBS MARC 21 format.
• Cells marked with green are defined in the CBS MARC 21 format. These tags are extensions to, i.e. these are not part of the Library of Congress and the OCLC (WorldCat) format. So, tags marked with green are defined in the CBS MARC 21 format.
• Cells with no color. These tags are "reserved" CBS MARC 21 tags; thus, these are non-existing tags now – for the main/master level, the local (LBD) and copy (LHR) level. These tags are only reserved for potential future use. Tags marked with no color may not be used in the CBS MARC 21 format now. So, when we need an extension of the CBS MARC 21 format or a new tag is defined by the MAC (MARC Advisory Committee), we already know what the CBS MARC 21 and CBS MARC 21 PICA+ tags will be.
• Tag descriptions marked with purple are specific OCLC MARC 21 (WorldCat) tags.

When other libraries use the same tags in their database and these tags need to be converted to a CBS in the CBS MARC 21 format, the tags must be used in the same way as these tags are defined in the OCLC MARC 21 format. If not, these tags need to be converted to CBS tags 0900 / 098A, 1900 / 198A, 2900 / 298A, 0901 / 098B, 1901 / 198B or 2901 / 298B, dependent on the specific situation. For more details, see: ... (under construction).

Obsolete MARC and OCLC MARC 21 tags

We have also noted the obsolete OCLC MARC and MARC 21 tags. They are of course not part of the format. So, the official MARC 21 and OCLC MARC 21 tags are the starting point. When a tag is obsolete, it is logical of course not to support it anymore.¹

1. When a library uses obsolete tags still, there are two options to solve this: the library which owns the data, corrects the data or OCLC EMEA converts the data to the correct tag. A second option is to store the data temporarily in a “garbage” tag to prevent that the data will be lost. For more details, see: ... (under construction).