Pascal Fortran Storage rules Basic concepts.
Dummy argument is a quantity in the specification of a procedure, function or subroutine.
Actual argument is a quantity in the call of a procedure, function or subroutine. The call is made from the calling procedure or program unit, often from the main program. When an argument is not specied as var then the content of the quantity will be copied to a new storage area, which will be used within the procedure. This means that , if the quantity is changed within the procedure, the new value will not be returned to the calling procedure. Such an argument is said to be a value parameter.