Library of Congress call numbers are arranged alphabetically and numerically. Read call numbers from left to right and from top to bottom.

Letters in the first line of the call number are alphabetical:

Numbers in the first line of the call number are in numerical order:

Letters in the second line are alphabetical:

Numbers in the second line of the call number are in decimal order. It is important to remember that there is an “invisible” decimal point between the letter and the number:

There may be a third line of letters and numbers. These will also be in alphabetical and decimal number order.

The last line of a call number may be a year. This indicates the publication date.