If you accidentaly run it the incorrect way with the front of the figure-8 Side mic pointing right instead of left, simply invert the polarity of the resulting Side signal before doing the M/S decoding, which is the same as pointing the mic the opposite way. The M/S stereo decoding will work fine even if you don't do that, except the resulting output will be swapped Left/Right. So alternately you could swap left & right channels after the M/S stage.. or leave it as is and see if anyone else even notices.