Cataloging and Classification/MARC

In 1901, the Library of Congress began selling catalog cards to other libraries. Rather than paying local catalogers to create catalog cards for items in their collections, these libraries could simply use cards created by the Library of Congress. The service led to a standardization of cataloging, and this sharing of bibliographic records can be seen to this days in cooperative cataloging programs such as OCLC.

In the 1960s, the Library of Congress developed a format to automate the production of these catalog cards. This format, Machine-Readable Cataloging (MARC), is still widely used today as the basis for most library catalogs. Though the use of such an old data format has frequently been critiqued, no clear successor to MARC has been identified, and the costs of converting thousands or millions of MARC records to a new format would be substantial. In 2011, the Library of Congress released a statement indicating that it was exploring alternatives to MARC.

What is a MARC record?
Each MARC record is composed of a leader, a directory, and several fields. The leader occurs at the very beginning of a record, and gives the system information about how to process the record. The directory is a computer-generated number that a cataloger typically never sees, telling the system where in a file each field starts and ends. The fields are character strings that contain data about the item being cataloged.

Each field starts with a tag -- a three-digit number that conveys what kind information is being stored (e.g. title, note, table of contents). Depending on the tag, it may be followed by one or two indicators -- numbers or letters that tell what flavor or form the information will take (e.g. will the person's name start with the last name or the first name? Is a 520 summary field specifically an abstract or a review?). Finally comes the actual information itself, which may be presented in one piece, or split up into separate subfields.

At first, tags may seem like completely arbitrary numbers, but there are some useful patterns in the MARC bibliographic record format that may help you remember them. Numbers starting with a 6 (the 6xx, in cataloging lingo) will always be subjects, and numbers starting with a 1 (1xx) will always be main entries. A tag ending in 00 will likely refer to a person's name, so a 100 is going to contain the name of a person who is the main entry (the primary author, in the case of books), and a 600 will contain the name of a person who is the subject of the item (the subject of a biography, for instance). Here are some handy things to remember:

MARC records can be used not only bibliographic records, but for authority records, holdings records, classification records, and community information records as well.

Fixed Fields
More accurately known as fixed-length fields, these fields include special codes that give ILSs information in a computer-friendly format, rather than a human-friendly one.

Limitations of MARC
1. MARC is virtually unknown outside of libraries. 2. MARC’s size limitations and its inability to convey complex relationships among entities. 3. inability to embed related objects in the record (book cover). 4.It’s computerized catalogue systems,shortage of manpower to design and operate machine-readable catalogues. 5. many have suggested that an XML schema should replace MARC