By default SmartPay uses a standard Mod Check algorithm; but just like everything in SmartPay, this can be customised if you have particular requirements.
Mask
The Mask simply indicates where the check digit occurs in the reference, using a "c". This is almost always the final digit.
#####c
Substitutes
This is used to map any letters appearing in the reference with numeric values for the purposes of the check.
X:10 C:11
Weightings
This is the weightings of the individual digits.
10 9 8 7 6 0
Modulus
The modulus to divide by.
11
Subtract From
The value to subtract from. (If you don't know this, it is almost certainly the same as the Modulus.)
11
Check Digit Map
This maps numeric values back to letters in the result.
10:X 11:0