Sorry,but I've worked with heidenhain more than two years and my opinion is that it's just waste of time to use this controller in ISO mode. It has very simple and powerfull conversational language (for milling applications) which makes programming much easier. I'm working with fanuc and heidenhain,every has it's own advantages and "black spots" but heidenhain excellent in it's conversational programming,once you understood it,will never forget,I swear I mean controllers series 355 and above..407,415... 426... worth to try...