library-of-congress

Library of Congress Classficiation System

The Library of Congress Classification System (LC), a sort of shorthand device for determining where a book belongs, is used in most of the IU Libraries. Every item in the library has a unique call number, telling us exactly where it belongs in relation to other items.

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

Read more about the Library of Congress Classfication Outline

Call Numbers

Every book you will be reshelving 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 the books belongs, and then to reshelve it. Call numbers serve to group items of a subject together. Call numbers are made up of at least 2 parts: Class number and Cutter number.

Library Code

The first line above the call number is simply an ownership marking to indicate that the book belongs to a specific library or a location within the IU South Bend library. The following example is a book from the THESES collection in the South Bend library. Some other examples of location codes are PER (Periodicals) or REF (Reference). Examples of other libraries include ERC (Educational Resource Commons) and B-EDUC (Bloomington's Education Library). Books in a general collection do not have this Library Code.

Class Numbers

The Class Number is a combination of letters and numbers. It's separated from the cutter number by a decimal point.  The class number to the right indicates that this periodical (library code PERIODICAL) belongs to the subject area Modern European Languages.

Class Numbers usually consist of 1 or 2 letters followed by numbers from 1-9999.  The number could contain a decimal point (not to be confused with the decimal separating class and cutter numbers).  Here are some examples in call number order :

QP

122

.M4

QP

122.3

.K33

QP

122.35

.L23

QP

123

.P23


The first unit is the Class Letter.  You first put the book in alphabetical order by this letter.  Then, after letter order, you put the books in numerical order.  For instance, once you have the Ps together, you can put them in order P, PA, PB, PC.  Then you put in order by number from P1 - P9999, PA1 - PA9999, etc.

NOTE:  There is only one class number without letters (older law books), and two areas (DKJ and KBA-KXZ) that have 3 letters.  Some parts of the K class have letters with no numbers.

Cutter Number

Class number organization is not specific enough to tell you where to put on the shelf.  Once you have books organized by class number, you must look at Cutter Numbers

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 Class Numbers.  Ordering cutter numbers as whole numbers rather than decimals is the most common shelving error.  The first element of a cutter number is always a letter and is followed by at least one number. 

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

  1. alphabetically by the first letter
  2. numerically, in decimal order, by the number after it
  3. alphabetically by the second letter
  4. numerically in decimal order, by the number after the second letter.

Here are some Cutter Numbers in order:

PQ

2349

.A12

1967

PQ

2349

.A36

D45

PQ

2349

.A4

E5

PQ

2349

.A67

1998


The cutter number usually contains information about the author or it may further subdivide a category.  The first cutter number is often the first letter of the author's  last 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.

Edition

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.  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:

F

103

.M12

F

103

.M8

1956

F

103

.M8

1967

F

103

.M8

1996

Series

Sometimes a single title will be published in several volumes (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:

AE

5

.W55

v.20

AE

5

.W55

.v21

AE

5

.W55

1996

v.20

AE

5

.W55

1996

v.21

Copy Numbers

In the past, before books libraries used computers to circulation collections, titles with more than one copy in the library had their unique copy number included as part of the call number. Today, since each books has a unique barcode attached, the copy number is no longer necessary for cases where there are multiple copies of the same book. You can ignore the copy number when putting books in order or reshelving items.

General Review

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:

  • alphabetically by the first letter(s) in the CLASS NUMBER
  • numberically, 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)

Congratulations!  You're ready to take the LC Test now.  When you hit the SUBMIT button, your results will be sent directly to your supervisor.  Do not worry, any items you miss will be reviewed during your training session.  Click the LC Test link below (or at the top of this screen).  Follow the instructions.  Good luck!