The source channel to use as first variable in the mathematical operations. This channel is optional.
If no source channel is linked, the Value setting is used instead.

The mathematical operation to use on the two channels. These are simple and common mathematical operations so we assume you have heard of them.

Add - adds the values of the source channel to the target channel
Substract - substracts the values of the source channel from the target channel
Multiply - multiplies the values of the source channel with the target channel
Dot Product - calculates the scalar (dot) product of two vector channels
Min - compares source and target channel and writes the minimum value into the target channel
Max - compares source and target channel and writes the maximum value into the target channel
Blend - Blends source channel into the target channel

The value for the math operations if no source channel is specified.