All it is, is a free walk on a long rein across the short diagonal of M to E (aim for just before E) then immediately another rein change across the short diagonal of E to F. So it's sort of like 2 sides of a triangle, odd but you can pick up marks here as M-E and E-F are marked separately.
If your horse is anything like my last pony and gets distracted in the free rein twiddle with the rein way from the judges view to try and keep their focus on you
At least you are one step ahead of me, when I did this test, I read it as free walk down the long side.... It wasn't till I watched the person before me do this and get beeped that I realised it was wrong, oopps!
Several others in the class misread it too