Dreamland,
Alpha lock function is active if AoA >8.5° or speed is lower than 148 knots.
The alpha lock function is only active with the flap lever at position 1. i.e. if you select flap zero they will not move if AoA is too high. However, if the lever HAS BEEN moved to zero, and AoA subsequently becomes excessive - THE SLATS WILL NOT BE LOCKED - they will continue to retract to zero .......
Man Flex
There is a "gate" at positions 1 and 3 to prevent excessive selections. Seems to work - I've been on the Bus for nearly 6,000 hours and have never gone from 2 or 3 to zero in one move.
A4