modulus 10 checksum algorithm; tab_checksum works for 14-digit only

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Article Type: General
Product: Aleph
Product Version: 20

Description:
Our item barcodes consist of 13 digits, where the last digit is automatically calculated from the first 12 using a left-to-right modulus 10 checksum algorithm. The DRA cataloging software does a reverse mod 10 calculation to make sure that any barcodes we enter for new items are valid. Since there is only a one-in-ten chance that a barcode with a random typo in it would pass the mod 10 checksum test, this makes it nearly impossible for us to enter invalid barcodes, even when typing instead of scanning. Is there any way to add such a check to our Aleph configuration?". >>

I think "checksum_create_codabar" can be used. This program is defined in tab_checksum (xxx50/tab/). It looks like that the "checksum" part answers our specification (/alephm/source/checksum/checksum_create_codabar.cbl). Please confirm.

Resolution:
tab_checksum is used for defining programs used for creation, validation and correction of barcodes (etc.)..

The checksum_create_codabar program is used to *create* codabar format barcodes. It sounds like what you need is a modulus-10 *validation* program. (The barcode already exists. They just need for it to be checked when it's typed in to make sure it's typed correctly.).

There is a "checksum_valid_codabar.cbl" program. My guess is that this routine is actually doing a mod-10 check..
I would have them put a:

CSV-Z30-BARCODE checksum_valid_codabar

line in the abc50 tab_checksum and try entering some item barcodes into new items.

The checksum_valid_codabar routine assumes that your barcodes are 14 digits (not, as in this case, 13 digits). If you enter a barcode which is shorter than 14 digits, it will issue this message in the pc_server log:.

Warning : cannot generate chksm for invalid barcode ....

or, for loaning/returning an existing barcode:

Item barcode checksum not valid

To make this work, the checksum_create_codabar.cbl and checksum_valid_codabar.cbl would need to be changed to calculate the check-digit for barcodes with lengths other than 14. (These program changes would be an enhancement requests.)

Article last edited: 10/8/2013