Sue de Coq

Take the two or three cells where a box and a line (row or column) cross. Together they hold at least two more digits than they have cells. Look for a group of cells in the line (outside the box) and a group in the box (outside the line) whose digits come from the crossing cells, with the two groups using different digits, so that the digits of all three groups number exactly as many as their cells.

Then these cells are a locked set. Remove from the rest of the line every digit of the three groups that does not appear in the box group, and from the rest of the box every digit that does not appear in the line group.

Tip: A Sue de Coq is a pair of almost locked sets with a special shape. If you know ALS-XZ it helps to read the diagram as three almost locked sets.

Notation

Sue de Coq: 9 can be removed from r1c5.