Function Calling (The GNU Awk User’s Guide)

From Get docs

9.2.3 Calling User-Defined Functions

Calling a function means causing the function to run and do its job. A function call is an expression and its value is the value returned by the function.

Calling A Function    Don’t use spaces.
Variable Scope    Controlling variable scope.
Pass By Value/Reference    Passing parameters.
Function Caveats    Other points to know about functions.