If you wrote the same thing in assembly language and, by convention, you return the value from a subroutine in the AX register. This function is not returning a

If you wrote the same thing in assembly language and, by convention, you return the value from a subroutine in the AX register. This function is not returning anything useful so you don't 'MOV AX,blah', yet your caller expected something in it, is it undefined? Does the AX register exist in the caller? Yes. Does it have a value? Yes. Is its 'value' undefined. Yes. Is there any undefined 'behaviour' of anything you told it to do? Not to me. Subtle maybe.