The big picture All functions, whether built-in or user-defined, generally can be described as subroutines that return a value or complete a task.

Random-number functions and CALL routines generate streams of random numbers from an initial starting point, called a seed, that either the user or the computer clock supplies. A seed must be a ...

First of all User Defined Functions as specified within the Formulas properties of your app. Just like Named Formulas. In the above example we can see that the structure is fairly similar.