Hi Harry - thanks for using the forum. The strict astronomical definition of azimuth is "the bearing of an object measured as an angle round the horizon eastwards starting from north as the zero point." Mitton, The Penguin Dictionary of Astronomy. Your point is well made. In the script Horoscope-Extra-Local Horizon Horoscope you will see the convention is adopted. This measurement is latitude dependent, so a southern hemisphere horoscope should show 0 degrees for the MC, as far as I know.
I wonder if Jean could have a switch to allow people to choose either definition. Some astrologers are rather wedded to the idea that azimuth is measured from the south point of the horizon. I'm not really sure why.
Best wishes. Ed