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Guide to the Library of Congress Classification System (LC)


What is a call number?

The Mary Livermore Library uses the Library of Congress Classification system when assigning call numbers to books and other items. A call number is an address which determines the item's location on the shelf.

Where are call numbers located?

When using BraveCat, the Library's online catalog, a call number usually accompanies the record of an item. In the catalog, the call number appears on one line. For example, the call number for The book of enlightened masters : western teachers in eastern traditions, found in BraveCat would look like this:

Image of a book record

The same corresponding call number found in BraveCat will be found on the spine of a book or item, letting you know its location on the shelf.

Image of a book

Image of a computer terminal

The Anatomy of a Call Number

The Library of Congress Classification uses a combination of letters and numbers to generate call numbers for books and other items. Each item you find in BraveCat or on a shelf in the Library, will have a Library of Congress call number consisting of both letters and numbers.

Image of an LC call number.


Book Title:
The book of enlightened masters : western teachers in eastern traditions
Author: Andrew Rawlinson
Call Number:
BL1032.R38 1998

  • The first two lines describe the subject of the book
    BL1032 = Asia--Religion, spiritual biography
  • The third line represents the author's last name
    R = Rawlinson
  • The last line represents the date of publication

 

Finding items on the shelf using call numbers

Since most Library of Congress call numbers consist of several letters and numbers, it is important to write down the entire call number when looking for books and other items on the shelf. It is equally important to be well versed in the numbering system in order to successfully locate your call number among all of the others on the shelf.

The first line of a call number may begin with one, two or three letters. These letters should be read alphabetically. A call number that begins with A is shelved before one that begins with B, C, etc.; and a call number that begins with QE is shelved somewhere between the one that starts with Q and the one that starts with QL.

Single letters are filed before double letters.

DC

DL

FA

The second line of a call number is made of a number that may have one or more digits. This line is read numerically. A call number with a smaller number in its second line is shelved before one that has a larger number for its second line.

QA 
50

QA 
55

QA 
76

QA 
76.15

QA 
76.73

The third line is the trickiest part of the call number. The letter is shelved alphabetically, and the number following the letter is treated as if it were preceded by a decimal.

PN
6231
.E259

PN
6231
.E29

PN
6231
.E4

PN
6231
.E74

PN
6231
.F44

When the top three lines are identical, look to the fourth line. If it contains a letter followed by numbers, items are organized alphabetically by letter, and within each letter by decimal number. (Note the number is treated as a decimal number even though there is no visible decimal point).

QE
862
.D5
L22

QE
862
.D5
L35

QE
862
.D5
L4571

QE
862
.D5
L461

QE
862
.D5
M3311

QE
862
.D5
M37

The final lines of the call numbers may include dates, volume indicators, issue numbers, copy numbers and other annotations such as supplement or index specifiers. These annotations are read after the call number.

Q
10
C 3

Q
10
C3
1933

Q
10
C3
1990

Q
10
C3
1996
copy 1

Q
10
C3
1996
copy 2

QD
1
A5
Vol. 1

QD
1
A5
Vol. 2

QD
1
A5
Vol. 2
Plates

QD
1
A5
Vol. 2
Supp.

 

Subject Headings

The Library of Congress assigns subject headings to every book that is given a call number. These subject headings represent what the book is about. Some books have one subject heading, some have several. In BraveCat, subject headings for each book are listed near the bottom of the item record.

Image of subject headings

Subject headings dictate the beginning of the call number, and play a major role in the location of items on the shelf. For instance, if a book's call number begins with the letter E, the main topic of the book will be American History. Because the Mary Livermore Library uses the Library of Congress system, books are grouped together on the shelves according to their subject, thus most of the books on American History will be found in the same area of the Library. When looking for books on particular subjects, it is often helpful to browse the shelf area where those subjects can be found.

For more Library of Congress subject classifications, consult the table below:

A - General Works N - Fine Arts QE - Geology
B - Philosophy-Religion-Psychology P - Linguistics QH - Biology
C - History (Civilization) PC - Romance Languages QK - Botany
D - History (Except America) PD - Germanic Languages QL - Zoology
E - American History PE - English Language QM - Human Anatomy
F - Local American, Latin American History PQ - Romance Literature QP - Physiology
G - Geography-Anthropology PR - English Literature QR - Microbiology
H - Social Sciences PS - American Literature R - Medicine
J - Political Science Q - Science S - Agriculture
K - Law QA - Mathematics T - Technology
L - Education QB - Astronomy U - Military Science
M - Music Scores QC - Physics V - Naval Science
ML - Music (Literature of Music) QD - Chemistry Z - Bibliography, Library Science

 

created 12/06 ach