A number part of type "Resolve checksum" can be configured to define a checksum by custom logic by a Resolvers.
The concatenation of all strings provided by number parts configured as Selected part serves as input (string) for the resolver.
In the example above a dynamic number part (see Dynamic (Number part)) "DEC" returns a 4-digit decimal number with "0" as a fill character.
These values are passed to the checksum resolver as the only "selected part" and stored in a variable "input".
This variable is evaluated by Calculate value. The formula used determines the remainder values ("%2" reads as "mod 2") after dividing "input" by a finite series of binary powers and adds up the results. Effectively, this sum is equivalent to the number of bits with value 1 in a binary representation of the input value. A decimal value of 19 ("0019" in image) converts to a binary representation of 1011 with three "set" bits. The checksum value returned is 3.
NOTE The formula in this example is not a proven checksum method and only used to illustrate the configuration procedure as such.