Stamp Numbering System - Catalog Numbering Systems

Catalog Numbering Systems

Numbering of stamps cannot be a purely mechanical process; it is a complicated undertaking that requires some editorial judgment. Over time, stamp numbers become a shorthand for collectors and dealers; in the United States, the Scott catalogue number "C3a" is instantly recognized as the Inverted Jenny.

The Scott system assigns plain numbers for regular mail stamps, and uses capital letter prefixes for special-purpose types, such as "B" for semi-postals and "C" for airmail. The numbers are generally consecutive; there are gaps among older stamps, where some numbered types were later renumbered, and among newer stamps where Scott has left numbers unassigned in the anticipation of additional stamps in a series. If more stamps than expected appear, Scott will add a capital letter as suffix, or if the change is very recent, it will renumber stamps. Minor variations, such as shades or errors, get a lowercase letter; so the "C3a" above indicates a variation (error in this case) on the third US airmail stamp.

The Gibbons, Yvert and Michel catalogs use different arrangements for numbering regular and special-purpose types, and attach different importance to variations in paper, perforation, watermark and other types.

Because of its commercial importance the publishers of the Scott Catalogue claim copyright on their numbering systems, and grant only limited licences for their use by others. The inconsistency with which Scott enforced these licences resulted in a lawsuit by Krause Publications (publishers of the Minkus Catalogue) for copyright infringement. After Krause filed a defence the suit was settled out of court, and Krause continued to reference the Scott numbers. It has been speculated that Scott was not successful . Attempts by philatelists to establish an alternative have not yet been successful.