Shelving at the IUB Libraries

Library of Congress

Classification System

Books on shelves in the Wells Library stacks The Library of Congress Classification System (LC) is used in the Main Library, the Campus Libraries and all of the Halls of Residence Libraries. Some of the libraries may use other classification systems such as the Dewey Decimal System depending upon the materials they hold. However, most libraries on the campus use LC. Libraries use the LC call number system as a shorthand device for determining where a book belongs on the shelves. Every item in the library has a unique call number, telling us exactly where it belongs in relation to other items. As a Library Assistant, knowledge of the call number system will be a tool you use to assist patrons, as well as reshelve and shelfread.

Read through the explanation of the LC system below. There is a test at the end of the explanation. Use the arrow keys or the scroll bar on the side of your browser window to move down the page.

Here's a general explanation of LC call numbers:

(Don't Panic! You DO NOT need to memorize this part!)
A General Works -- includes encycolpedias, almanacs, indexes
B-BJ Philosophy, Psychology
BL-BX Religion
C History -- includes archaeology, genealogy, biography
D History -- general and eastern hemisphere
E-F History -- America (western hemisphere)
G Geography, Maps, Anthropology, Recreation
H Social Science
J Political Science
K Law (general)
KD Law of the United Kingdom and Ireland
KE Law of Canada
KF Law of the United States
L Education
M Music
N Fine Arts -- includes architecture, sculpture, painting, drawing
P-PA General Philosophy and Linguistics, Classical Languages, and Literature
PB-PH Modern European Languages
PG Russian Literature
PJ-PM Languages and Literature of Asia, Africa, Oceania, American Indian Languages, Artifical Languages
PN-PZ General Literature, English and American Literature, Fiction in English, Juvenile Literature
  PQ -- French, Italian, Spanish, Portuguese Literature
  PT -- German, Dutch, and Scandinavian Literature
Q Science -- includes physical and biological sciences, math, computers
R Medicine -- includes health and human sexuality
S Agriculture
T Technology -- inluces engineering, auto mechanics, photography, home economics
U Military Science
V Naval Science
Z Bibliography, Library Science

LC Call Numbers:

Parts, Order, and Organizing

(You DO need to memorize this part!)

Call Numbers:
Every book you will be in contact with will have a call number attached to it. The label is usually on the spine of the book. We use the call number label to help us determine where each book belongs, both for reshelving and for assisting patrons.

How to read LC call numbers:
Call numbers are read left to right, top to bottom, looking at one part of the call number at a time. Below is an explanation of the parts and what you need to know about them to get books into proper call number order and reshelve or shelfread them.

Library Code:
The first line above the call number is simply an ownership marking to indicate that the book belongs to a specific library. The example to the right is a book from the Education Library. These labels are necessary because library users may return books to a different library than the one from which they borrowed it. Research Collections in the Wells Library is the only location that does not indicate ownership on the call number label. If you find a book in the library where you work it is important that you place it in the appropriate location so that it will be returned to the proper library. Your supervisor will go over this during your training session. Some other examples of location codes are OPT (Optometry Library), FINA (Fine Arts Library), EDUC (Education Library).
Shelf label reading "EDUC LA 631.5 .J49 1998"

Class Number:
Call Numbers serve to group books of the same subject together. Every Call Number has at least two parts: the Class Number and the Cutter Number. The Class "Number" is actually a combination of letters and Numbers. The Class Number and the Cutter Number (see: "Cutter Numbers" below) are separated by one decimal point. The Call Number to the right has the Class Number marked. Here the QP indicates that this is a book on Science -- Physiology. The 398 further specifies that, within the broad QP subject, this is a book on Neurophysiology.

Class Numbers usually consist of 1 or 2 letters, followed by a number from 1 to 9999. The number could contain a decimal, such as PA 258.43. Here are some Class Numbers in the proper order (the Class Number is indicated in red.)

QP 122
QP 300

QP 398

QP 442

The first "unit" of the Call Number is the Class Letter -- you first put the book in alphabetical order by this letter. Then, after letter order, you put books in numerical order. So for instance, once you have all the "B"'s together, you can then begin to order them numerically from B 1 to B 9999.

NOTE: There is only one Class Number without letters [older law books in the range 6300 to 6499], and two areas [DJK and KBA-KXZ] that have three letters. Some parts of the class K have letters without numbers.

Cutter Number:

Class Number organization is not specific enough to tell you where each book belongs on the shelf -- once you have books organized by Class Number, you have to look at the Cutter Number(s).

The decimal point which comes directly before the first Cutter Number is there to indicate that this number is always a decimal and not a whole number like the Class Numbers. Ordering Cutter numbers as whole numbers is one of the most frequent shelving errors. The first element of the Cutter Number is always a letter, and is always followed by at least one number.

Shelf label reading "PR 6037 .C94 D4 1975"

If necessary, a second Cutter Number will be added after the first to further specify the location of the book. We take each element or unit of the Cutter Number one at a time. So within a particular Class Number, we then place the books in order:

a) alphabetically by the first letter
b) numerically, in decimal order by the number after it
c) alphabetically by the second letter (if there is one)
d) numerically, in decimal order by the number after it

Here are some Cutter Numbers in order ( the Cutter Numbers are indicated in red ):

PQ 2349
PQ 2349
PQ 2349
PQ 2349
The Cutter Number usually contains information about the author, or it may serve to further subdivide the subject. The first Cutter number is often the first letter of the author's name -- for instance, .S27 for Jane Smith -- and the numbers specify which exact author it is -- so this Jane Smith is not the same Jane Smith identified by .S28.

FYI: The Cutter Number is named after the librarian who developed this part of the LC classification system.


In many cases, the same book by the same author will be reprinted several times. In that case, each of the editions will have the same Call Number, but they will be specified by an edition date.

The edition date comes directly after the Cutter Number, and is the next unit to look at when you're placing books in order. For older books, the date of the first edition was not printed on the Call Number, but there is still an "assumed" edition date- a book without a date must be the first edition.

Here are some Edition Dates in order ( the Edition Dates are indicated in red ):

Shelf label reading "PR 6037 .C94 D4 1975"

F 103


Sometimes a single title will be published in several volumes (as in, for instance, encyclopedias). In these cases, a volume number comes after the edition date to specify the order of the books within the series.
Here are some Call Numbers with Series in order ( the Series is indicated in red )
Shelf label reading "PR 6037 .A89 Z48 1997 v. 4"
AE 5
v. 20

AE 5
v. 21

AE 5
v. 20
AE 5
v. 21

Note that books are placed in order by edition before they are ordered by volume-- remember that the edition date comes before the volume number even in cases where the edition date is "assumed".

Copy Numbers:

In the past, before books were charged out using computers and scanned barcodes, titles with more than one copy in our library had their unique copy number included as part of the call number. Today, since each book has a unique, machine-readable barcode attached, the copy number is no longer necessary for cases where there are multiple copies of the same book. You can effectively ignore the copy number when putting books in order or reshelving them, as long as you shelve two books with exactly the same call number right next to each other. However, to be consistent, you may wish to shelve them in order by copy number. Shelf label reading "PR 6037 .A89 L86 1972 c. 2"

Date Groups:
If a date appears between the class Number and the Cutter Number it does not indicate the publication date, but further subdivides the subject of the book. For instance, if the subject is "strikes at coal mines" the date of a particular strike might be used. Other examples are events that recur more or less regularly like meetings of associations or political parties.

Here are some examples of Call Numbers with Date Groups in order (the Date Group is indicated in red)

JK 122

JK 123
JK 123
JK 123

For books with the same Class Number [JK 123]: Shelve books without Date Groups are shelved after those with Date Groups.

Special Collections Codes (Main Library Only):
There are a number of special collections in the Main Library. These collections are special locations within the Research Collections stacks. The Special Collections Code is in the same location where you would find the Library Code. For example, the Folklore is a Special Collection. Below are some examples of other special collections:

Shelf labels from various special collections in the Wells Library

Call numbers are read left to right, top to bottom, looking at one part of the call number at a time. Call numbers are shelved as follows:

  • alphabetically by the first letter(s) in the Class Number.
  • numerically, by the Class Number.
  • alphabetically by the first letter in the Cutter Number
  • numerically, in decimal order by the Cutter Number
  • alphabetically by the letter in the second Cutter Number (if there is one)
  • numerically, in decimal order by the second Cutter Number (if there is one)
  • chronologically by the edition date
  • numerically by the volume number (if there is one)

Now you are ready to take the test. The test results will be submitted via e-mail to your supervisors. This will help the supervisors know how well you understand the LC call number system. Do not worry, any items that you miss on your test will be reviewed during your training session. Click the "LC Test" directly below and follow the directions from there.

LC Test

Last Updated: July 25th, 2012
Comments: Collection Management