The FUNCTION statement marks the beginning of a  function  subprogram  and
  defines the subprogram's parameters.

  Example

  FUNCTION INTEGER COMPUTE (A, B, C$)
      .
      .
      .
  END FUNCTION

1  –  Syntax

      FUNCTION data-type func-name [pass-mech] [([formal-parm],...)]

               [statement]...

      { END FUNCTION [exp] }
      { FUNCTIONEND [exp]  }

      pass-mech:  { BY DESC  }
                  { BY REF   }
                  { BY VALUE }

                              {unsubs-var-name            }
      formal-parm:
      [data-type]{array-name([int-const],...)}[=int-const][pass-mech]
                              { [ , ]...                  }