A type 'MOD 10' number part creates a check digit according to the Luhn-Algorithm, also known as 'Modulo 10' or 'mod 10' algorithm as well as the Double-add-Double-method.
The Repeatable element Selected part accepts references to other number parts, which are concatenated as input to the checksum calculation.
â–ºIMPORTANTâ—„ The algorithm accepts decimal digits (0-9) exclusively. All other characters (letters or special characters) are omitted from the concatenation of values provided by Selected parts. Effectively, this makes the checksum calculation robust against non-numeric fill characters or separators. On the other hand dynamic number parts (see Dynamic (Number part)) should not specify base values > 10.
Components in example:
Country: Fixed (Number part) with the value 400 (prefix for Germany)
Company: Resolve value (Number part), extracting a 4-digit company code from a text attribute in the data context
Article: Dynamic (Number part), automatically incremented 5-digit article code
Since the preview (right in picture) does not feature a data context for the Resolve value (Number part), the company code resolves as '0000'.
â–ºNOTEâ—„ For obvious reasons it does not make sense to include the number part for the checksum as a Selected part.