Bishop and Pawn vs. Bishop

Centurini's Rule: with the kings in vertical opposition, if both of the stopping diagonals of the pawn are at least four square then the defender can draw.

The winning technique is:
1) driving off the enemy bishop from one diagonal;
2) interfering along the other diagonal

The drawing technique is:
1) if the king gets in front of the pawn on a square of the opposite color of the enemy bishop then it's an easy, ironclad draw;
2) if the king can't get in front of the pawn, then the basic defensive principle becomes king behind king

Both stopping diagonals must be at least four squares.