1. My mistake I should have said MAN 06L
2. when the approach is surveyed/tested 100 ft above the runway threshold on the glide path is calculated and ground beneath that point in space (most likely approach lights not runway) is also surveyed if this happens to be a small mound it is quite feasible that the RA displayed when the ac is 100 ft above threshold elev may be 80 ft. Your ops manual, if your submission for cat2 approval was thorough enough, should have guidance on this to avoid pilots thinking the minima they use is rubbish.
3. By virtue of the fact most airports don't surround themselves with small hills it is more likely to have a dip in the ground surrounding a runway hence you often see CAT 2 minima of 105 or 110. This is still 100ft above runway threshold.
4 CAT 3 is very definitely above the runway at decide 50ft is therefore correct.
5. MAN 06L has minima for Cat2 for catB ac but not C/D due to erroneous RA readings at decide associated with the higher speeds and the river cutting below. CAT3 is permitted all cats
Hope this clarifies my point.
IN