5-digit supplemental barcodes are used on books to indicate a suggested retail price.

The first digit of the supplement indicates the currency in which the price is expressed. A "0" represents a price expressed in British Pounds whereas a "5" represents a price expressed in U.S. dollars. The remaining 4 digits of the supplement indicate the price.

A supplementary code of "90000" means the book has no suggested retail price. In most stores, this does not mean you make take the book without paying .

A supplementary code of "99991" indicates a complimentary copy of the book. This normally means "free." A retailer that is charging you for a book marked "99991" merits suspicion, but we still don't advocate walking off with such a book without paying for it.

Supplementary codes of 90001 to 98999 are used by some publishers for internal purposes. As an external user it is not generally possible to get much useful information from such supplemental barcodes due to the very fact that they are encoding some information internal to the publisher.

The supplementary code "99990" is used by the National Association of College Stores to mark used books. Don't pay "new" prices for books marked with this supplementary code.


1. Left-hand guard bars, encoded as 1011.
2. First data character, encoded using the appropriate parity pattern (see below).
3. Character seperator of 01.
4. Additional characters, encoding using the appropriate parity pattern, with separators of 01.

There is no specific "end" or "stop" character. The barcode is assumed to end when a character separator (01) doesn't follow a valid character.

The component characters of the barcode are encoded using the "left-hand odd" and "left-hand even" encoding character sets from the EAN-13 encoding standard. Whether a character is encoded using odd or even parity varies depending on whether the barcode is a 2-digit or 5-digit supplement. Essentially, the parity of the characters constitutes a rather crude checksum which is used to validate the integrity of the barcode.