In .NET COBOL, parameters can only be passed by value for function types.
function-id myFunction. procedure division using by reference myParam as binary-long. *> this causes the error ... end function. function-id myFunction. procedure division using by value myParam as binary-long. *> this is correct ... end function. function-id myFunction. procedure division using myParam as binary-long. *> this is correct - by value assumed ... end function.