Each cataloging record has a control number form the block of numbers supplied by the Cataloging Distribution Service for use in the Maps database. The control number is also known as the record identification number (RID) and as a card number.

The control number is a six-digit number preceded by a two-digit designator for the year of cataloging.

As the control number represents the most permanent unchanging identification for an item, it is extremely important that the control number for an item be transcribed correctly.

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