Call Numbers & Library of Congress Classification System

Shelving/Filing Rules of LC Call numbers

Single letters are filed before double letters:

The second part of a call number is made up of a number that may have one or more digits. This line is read numerically. A call number with a smaller number is shelved before one that has a larger number. Some of these numbers may be divided by a point: these are also read numerically (smaller numbers are shelved before larger numbers).

The third part is the trickiest part of the call number. This part of the call number is called the "cutter". The numbers in this part are treated like decimals.

Follow these general rules when dealing with cutter numbers:

1. Treat the letter of the cutter number alphabetically. For example, cutter numbers beginning with .B are shelved before those starting with .E.
2. Smaller first digits after the letter are shelved before larger ones. For example, all cutter numbers beginning with .E3 would be shelved before all cutter numbers beginning with .E4, and those would be shelved before cutters beginning with .E8.
3. Smaller second, third, etc. digits are shelved before larger ones. For example, cutters beginning with .E35 are shelved before cutters beginning with .E39. Likewise, for the third number: .E353 is shelved before .E355 and .E359.
4. Items with only one digit after the letter are shelved before items with multiple digits beginning with the same number(s). So, the cutter number .E3 is shelved before .E35 , which is shelved before .E359.

Sometimes there are TWO cutter numbers in a call number. The first cutter, in these cases, is related to the subject of the work. The second cutter is related to the author. The shelving order of the second cutter follows the same four rules described above.

Sometimes, the top of the call number has the item's location: "Ref" for Reference room, etc. The final lines of the call numbers may include copy numbers, issue numbers, volume indicators and other annotations such as supplement or index specifiers. For example, the call numbers below are shelved in Reference: