C function prototypes must always return a type of item and must always pass at least one parameter. If no parameters are shown, then the function declaration is not a function prototype and the Header-to-copy utility does not generate any COBOL CALL prototype. If no return type is shown, then the return type is assumed to be of type int.
If a function is not to return anything, then a function prototype uses a return type of void. The Header-to-copy utility translates this, omitting any RETURNING clause. If a function is not to have any parameters, the function prototype will have one parameter of type void. The Header-to-copy utility translates this by omitting the USING clause, together with any BY VALUE or BY REFERENCE clause.