CAS command question

[parisse]

DrD, I think you are still confused. The parser steps returns the expression as is (unevaluated) but that does not change the CAS logic: you need to eval the expression otherwise nothing happens and you would get left(x>2) returned when you type left(x>2) (exactly like if you enter quote(left(x>2))).
I don't understand why it's so important for you to keep the ordering, since I have explained how you can program the same functionnality whatever the order is. In fact it's even better because the resulting program is more general.