Aligned Triple Exclusion

The cells B3, A4 and A6 can together accept various combinations of values. But some combinations of values can be excluded, because they would leave some cells with no potential values.

More precisely, the following combinations of values are not possible for the cells B3, A4 and A6:
0, 9 and 9 because the value can occur only once in the region
1, 8 and 9 because the cell A2 must contain 1 or 9
5, 8 and 9 because the cell B6 must contain 5, 8 or 9

Because some potential values of A6 occur in none of the remaining combinations, they can safely be removed.