Call Numbers: Common Patterns of LC Call Numbers

Scope:  Explains and provides examples of valid Library of Congress call numbers as they appear in bibliographic records.

Contact:  Natalie Sommerville

Unit: Resource Description  Resource Description

Date last reviewed:  04/08/2021

Date of next review:  06/30/2021

The usual pattern for an LC number for a monograph is:

Classification number, $b cutter, date

The classification number always starts with a letter (or 2 or 3) and contains [a] number[s].   It can also contain a decimal followed by a number and/or a decimal followed by a letter and number[s].   The cutter is usually a letter plus number[s].  The  length of both classification and cutter varies greatly. 

B2 $b .F324  2009
B20.6 $b .R123 2009
NB165.N4 $b S7 1950
PN1998.3.R54 $b R53 2009

(note that there is a decimal immediately following the $b in the second two examples, but not in the first two.  The rule is that there needs to be a decimal before the 1st cutter, but the 1st cutter may be part of the classification number OR the beginning of the $b.   For practical purposes it doesn't matter whether there is a cutter after $b, because the catalog and the label program will space according to the $b.  So copy catalogers need not be concerned about this fine point.)

For PZ numbers (juvenile literature), there may be succession of letters rather than a cutter:

PZ7.A22 $b Po 1859  or
PZ7.A47 $b R5 1937

Dates may appear as elements of the classification number.  For example, numbers for hurricanes include the date of the hurricane

HV636 2005 .L8 $b F123 2009

Small letters may follow either the cutter or the date:

B20.6 $b .R123 2009b

B20.6 $b .R123 2009x

B20.6 $b .R123x 2009

RARELY, there is no cutter number

E457.91 $b  1953.

RARELY, an additional cutter may follow a date in the $b.  This is most common for maps. Call numbers for maps may also contain colons, for example G6713.F7:3G6P2 1976 $b .L5. 

RARELY, the date may be replaced by an element that looks like a cutter but is actually code for the date.  This occurs in literature.   For example, the number for the collected works of Mark Twain, published in 2009 is:

PS1300 $b G09

SOME EXAMPLES OF INCORRECT OR INCOMPLETE CALL NUMBERS THAT NEED ATTENTION FROM AN ORIGINAL CATALOGER

No $b

F3704.5

HD70 C2132 Q3 D278 2008

(Even if there were a $b the number above would be wrong, because there should not be more than two cutters)

Not a number at all:

LAW