Inherits Operation.
This operation has two inputs, A and B. If A and B are both given, the operation uses A and B to produce the result. If only A is given, the operation uses an internal spatial layer called R to produce the result. The values in R are accrued every time the operation is executed, and can be reset using the 'Reset' dependancy. Two-input operations include addition, subtraction, multiplication, division, maximum, minimum, magnitude and script operations. The script operation uses a JavaScript syntax in which R, A and B can be used, and is read from the 'Script' input. The script must be in the form of a one-line expression such as 'R = A + B', or 'R = A > B ? A : B' One-input operations include distance, absolute value and alignment operations. The distance operations builds a distance map from the input grid using the negative-positive crossing as the zero distance interface. The alignment operation carries out boundary alignment on the boundaries of the Grid. The scalar operations use a single scalar input to operate on the grid, including setting the value of the grid as well as addition and multiplication by the scalar.
