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Check Digit

A check digit is an extra character that is appended to the end of a barcode to verify the accuracy of the barcode symbol. The check digit value is derived from the sum (or weighted sum) of the values of the previous characters in the barcode. Use the Check Digit option to specify whether check digits are added to your barcodes.

Why Check Digits Are Used

Data entry automation with a barcode reader is many times more reliable than manual data entry with a keyboard, but the possibility of decoding errors can never be statistically eliminated. For example, a sudden jerk in a user's scanning motion or a printing defect in a barcode can cause a substitution error to occur. In situations where a substitution error might catastrophically affect the integrity of your database, we strongly recommend that you use check digits.

Although check digits do not completely eliminate the possibility of substitution errors, they do reduce their likelihood even further, which improves data integrity.

How Check Digits Work

When a barcode reader that is configured to look for check digits scans a barcode that contains a check digit, it re-performs the same calculation that BarTender performed when it generated the check digit originally. The barcode reader then compares its computed check sum value to the value of the check digit that was printed by BarTender.

If the two values are the same, the barcode reader transmits the barcode message. If the two values are different, the barcode reader determines that an error occurred, and no barcode characters are transmitted. The user must scan the barcode message again.

Symbology-Specific Information for Check Digits

Several symbologies are always printed with check digits. Therefore, when you select and configure these barcodes, the Check Digit option is selected by default and cannot be changed.

Some symbologies do not include a conventional human readable interpretation for the check digits. For these barcodes, the Hide Check Digit option on the Human Readable property page of the Barcode Properties dialog is selected by default and cannot be changed.

If the check digit that you want is unavailable, and if you want to append an additional check digit or define a custom check digit algorithm, you can do so by using VBScript. For more information, refer to Creating Custom Check Digits.

Supported Symbologies

This option is available for the following symbologies:

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