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:

Tag	What it means
0xx	The book's identifying number (ISBNs, ISSNs, OCLC numbers, LC control numbers, LC and Dewey classification numbers)
1xx	Main Entries
2xx	Titles, publishing info, editions
3xx	Physical description, etc.
4xx	Series information
5xx	Notes, such as item summary or if it includes a bibliography
6xx	Subjects
7xx	Added entries, information about items related to the item being cataloged
8xx	Series added entries, information about a particular library's holdings
9xx	Local use (i.e. pretty much whatever your library wants to do with it)

Tag ends in	What it means
X00	Personal name
X10	Corporate name (the name of an organization, government, business, group of people, or a person acting on behalf of a government)
X11	The name of a meeting or conference
X51	Geographic name (the name of a place)

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

Leader

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.

Variable-Length Fields

Indicators

Subfields

Common variable-length fields

Different Views of MARC Records

Raw MARC

00490cam a22001453 4500005001700000008004100017016001800058029002100076029002000097029002000117100003700137245011400174260003200288300002400320�20120905083316.0�890802s1899 xx 000 0 eng d�7 �a002622267�2Uk�1 �aUNITY�b123402042�1 �aUKRNI�b10162817�1 �aUKRNI�b10162818�1 �aNesbit, E.�q(Edith),�d1858-1924.�14�aThe Story of the Treasure Seekers. Being the adventures of the Bastable children in search of a fortune, etc.� �aT.F. Unwin:�bLondon,�c1899.� �axii. 296 p. ;�c8°.��

Human-Readable MARC

LDR  00626cam a22002053  4500
005  20120905083316.0
008  890802s1899    xx            000 0 eng d
0167 	$a002622267$2Uk
0291 	$aUNITY$b123402042
0291 	$aUKRNI$b10162817
0291 	$aUKRNI$b10162818
1001 	$aNesbit, E.$q(Edith),$d1858-1924.
24514	$aThe Story of the Treasure Seekers. Being the adventures of the Bastable children in search of a fortune, etc.
260  	$aT.F. Unwin:$bLondon,$c1899.
300  	$axii. 296 p. ;$c8°.

MarcXML

<?xml version="1.0" encoding="UTF-8" ?>
<marc:collection xmlns:marc="http://www.loc.gov/MARC21/slim" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.loc.gov/MARC21/slim http://www.loc.gov/standards/marcxml/schema/MARC21slim.xsd">
  <marc:record>
    <marc:leader>00490cam a22001453  4500</marc:leader>
    <marc:controlfield tag="005">20120905083316.0</marc:controlfield>
    <marc:controlfield tag="008">890802s1899    xx            000 0 eng d</marc:controlfield>
    <marc:datafield tag="016" ind1="7" ind2=" "><marc:subfield code="a">002622267</marc:subfield><marc:subfield code="2">Uk</marc:subfield></marc:datafield>
    <marc:datafield tag="029" ind1="1" ind2=" "><marc:subfield code="a">UNITY</marc:subfield><marc:subfield code="b">123402042</marc:subfield></marc:datafield>
    <marc:datafield tag="029" ind1="1" ind2=" "><marc:subfield code="a">UKRNI</marc:subfield><marc:subfield code="b">10162817</marc:subfield></marc:datafield>
    <marc:datafield tag="029" ind1="1" ind2=" "><marc:subfield code="a">UKRNI</marc:subfield><marc:subfield code="b">10162818</marc:subfield></marc:datafield>
    <marc:datafield tag="100" ind1="1" ind2=" "><marc:subfield code="a">Nesbit, E.</marc:subfield><marc:subfield code="q">(Edith),</marc:subfield><marc:subfield code="d">1858-1924.</marc:subfield></marc:datafield>
    <marc:datafield tag="245" ind1="1" ind2="4"><marc:subfield code="a">The Story of the Treasure Seekers. Being the adventures of the Bastable children in search of a fortune, etc.</marc:subfield></marc:datafield>
    <marc:datafield tag="260" ind1=" " ind2=" "><marc:subfield code="a">T.F. Unwin:</marc:subfield><marc:subfield code="b">London,</marc:subfield><marc:subfield code="c">1899.</marc:subfield></marc:datafield>
    <marc:datafield tag="300" ind1=" " ind2=" "><marc:subfield code="a">xii. 296 p. ;</marc:subfield><marc:subfield code="c">8°.</marc:subfield></marc:datafield>
  </marc:record>
</marc:collection>

OPAC Views

UNIMARC

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