## All books in the Library are shelved in call number order according to the Library of Congress system. This system flows both alphabetically and numerically, using multiple lines.

## FIRST LINE

The **first line** will have from one to three letters, and indicates order alphabetically, the same way as a dictionary. For example:

A | AA | AB | AC | AD | AE | AF | AG | AH | AJ | AK | ….. AZ |

Not all the letters will be used. These examples are to give you a rough idea of how the system works. Here is an example of the first line with three call numbers.

KFA | KFB | KFC | KFD | …… KFX |

## SECOND LINE

Next, when the first line of the call number is identical, then the **second line** is used to determine order numerically. The second line is a **whole number**.

For example:

PS | PS | PS |

65 | 585 | 3515 |

(The second line of the call number PS **65** is read as **sixty-five.**)

(The second line of the call number PS **585** is read as **five hundred, eighty-five.**)

(The second line of the call number PS **3515** is read as **three thousand, five hundred and fifteen.**)

## SECOND LINE WITH A DECIMAL

Sometimes, the second line which is a **whole number** is followed by a decimal. **The whole number comes first, followed by the decimals**, which go in order from smallest to largest. You must **match the decimal number-for-number** making sure the smallest numbers go first.

PS | PS | PS |

3515.115 | 3515.12 | 3515.5 |

These books would go on the shelf after any books with the PS 3515 call number.

## THIRD LINE

If the first two lines are identical, then you should go to the **third line** to determine call number order. **The third line ALWAYS begins with a decimal point followed by a letter**, and then one or more digits. Like the previous example, the numbers go from the smallest to the largest, **matching number-for-number.**

Look at the following example:

PS | PS | PS | PS | PS | PS |

3515 | 3515 | 3515 | 3515 | 3515 | 3515 |

.M112 | .M12 | .M135 | .M2 | .M213 | .M23 |

With this example, it would appear at first that "2" should come before "112." However, if you compare the first digit after the M, **“1"** comes before **“2"**, so this determines the order. **Remember, the third line is NOT read as a whole number!**

## FOURTH LINE

The **fourth line** is a continuation of the third line. **It should be read alphabetically, and then as a decimal.** If the first three lines of the call number are the same, then you must go to the forth line.

For example:

PS | PS |

3515 | 3515 |

.R3457 | .R3457 |

U137 | U17 |

It would appear at first that "17" should come before "137." The first digits after the U, **“1”** is the same for both yet the next digit **“3”** is before **“7,”** so this determines the order. **Remember, the fourth line is NOT read as a whole number!**

## NOTHING COMES BEFORE SOMETHING RULE:

The call number with less information goes before the one with more.

For example:

PS | PS |

3515 | 3515 |

.R3457 | .R3457 |

2006 | U137 |

2003 |

**Another Example:**

If two call numbers are the same, except that one has an additional line beyond the other, the call number with more information is considered to be higher.

For example:

PS | PS |

3515 | 3515 |

.R3457 | .R3457 |

U137 | U137 |

2006 |

## OTHER ODDITIES:

If you see a call number with the third line that looks like a **zero, it is really the letter O.** Example, PS 3515 .O17

If you see a call number with the third line that looks like a **one, it is really the letter I.** Example, PS 3515 .l17