Unique Rectangle Type 3
The rectangle's spare candidates form a subset with other cells of the same house, and that subset clears candidates in the usual way.
How it works on this board
The roof's extra 2 and 5 and the outside cells form an equal-cells, equal-candidates subset
7
4
3
8
9
1
4
1
7
6
6
1
1
4
8
5
2
3
2
1
8
8
3
1
6
4
6
4
6
8
3
9
1
7
8
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