Penn State University Libraries - Intro to MARC Tagging

MARC (MAchine Readable Cataloging), developed by the Library of Congress in the mid-1960's, is a standardized method of storing cataloging information so that it can be easily processed by computer. In addition to the original book format, the Library of Congress has developed formats for serials, maps, music, manuscripts, and audio-visual materials (films).

MARC was initially designed as a means of communicating cataloging information electronically amongst libraries; however, libraries (including the Pennsylvania State University Libraries) have adopted it as a means of storing information as well. The Pennsylvania State University Library's in-house catalog is called The CAT.

Some computer programs use the fixed field approach to data storage, in which each field is a specified number of characters in length. This approach works well with some databases (such as mailing lists) in which there is an obvious limit to the length of each field, as well as some fields which are always the same length (such as zip codes). With cataloging information, though, there is no way to predict how much space should be alloted to each piece of information; an author's name, for instance, could be 8 characters long, or more than 30 characters long. If each author field were more than 30 characters long, the unused spaces would take up a tremendous amount of wasted space in the Cat.

To deal with variable length data, the Library of Congress uses a variable field approach. Each cataloging record is free format, with no wasted space.

Each piece of data, or data element, in a catalog record is assigned a three digit label called a tag, which precedes the field. The tag for a personal author, for example, is 100.

100    1#    Doyle, Arthur Conan.

This method allows us to insert any number of fields into a cataloging record, with each field being of any desired length (with the exception of the 008/fixed fields).

Each field may contain one or several data elements of related information. For example, the author field may include, besides the author's name, his/her title, qualifying information, and/or dates of birth and death. Each bit of information is contained in what is called a subfield.

Each subfield is assigned a two character code which consists of the delimiter symbol (in The CAT, a vertical bar, also called the pipe sign) and a lowercase letter or a number for the subfield code. In the following example, the author's name is in subfield |a, his title in subfield |c, and dates of birth and death in subfield |d.

100    1#    [|a]Doyle, Arthur Conan,|cSir,|d1859-1930.

In The CAT, the default delimiter for the first subfield is |a, since |a is almost always the first subfield. When it is |a, it does not display on the screen.

For some fields, the tag and the subfield codes are all that is needed to completely identify the information in the field. Other fields, though, require more identification. For example, there is more than one type of call number: a local call number assigned to a book can be Library of Congress classification, or Dewey. The CAT has no way of knowing which type of local call number may appear in an 090 field unless we use indicators to indicate to the CAT the type of call number that is being used.

Indicators are located between the field number and the first subfield. In the following example, the first indicator (0) tells The CAT that the call number is Library of Congress classification, and the second indicator (1) tells The CAT that the call number is the same as the one assigned by the Library of Congress.

090    01    RC489.C63|bC646 1984

The first indicator in the next example (1) tells The CAT that the number is Dewey, and the second indicator (0) tells The CAT that the call number is NOT the same as the one assigned by the Library of Congress.

090    10    133.8|bR318d

Indicators for different fields have different meanings. Some fields have two indicators; some have one indicator (in which case the other indicator is blank); and some have no indicators at all (both indicators are blank). Fields with only one indicator can have the indicator in either position.

Indicator examples:

Label	Tag	Ind.	Contents
LCCN	010		85082138
ISBN	020		0448106809
Cataloging source	040		PSt|cPSt|dWaOLN
Personal Author	100	1#	Roth, Harold.
Title	245	10	Autumn days /|cHarold Roth.
Publication info	260		New York :|bGrosset & Dunlap,|cc1986.
Physical descrip	300		[12] p. :|bcol. ill. ;|c17 cm.
Series	490	#0	Babies love
Series	490	1#	Babies love photo board books
General Note	500		Cover title.
Local note	590		Description based on surrogate.
Subject	650	#0	Seasons|vJuvenile literature.
Subject	650	#0	Autumn|vJuvenile literature.
Added title	740	#0	Babies love autumn days.
Series	800	1#	Roth, Harold.|tBabies love photo board books.
Holdings	949		QB637.4.R68 1986|wLC|i000021317668|mYORK|d07 /08/1999|kSWARTZ|lSWARTZ|rY|sY|t JUVENILEBK
Held by	596		YORK