What you also need to be aware of is that the G0, G1 and F words are all modal. That is to say they will stay selected unless you change them. For instance, if you typed G1 X25 F50 into the MDI and hit return, if you then type in just X50, your machine will make the move at the last feedrate i.e. 50. If your last move was a G0 then it would rapid.
This can catch you out as Mach doesn't care whether the input was from a program or the MDI. Because of this, it is always safest to actually type in full code the first time you use the MDI in a session.
Mike