In X-Wing, we had only 2 row and columns for a particular given number. In Swordfish, This extends to more than 2 rows or columns. Let us take number 6 in this example. For Column 2, Column 5 and Column 9, the 6 can only appear in Row 3, Row 4 and Row 9. (circled cells) . Hence for these 3 rows, the number can only be in Column, 2, 5, and 9 and no where else. This leads to elimination of the number 6 in the highlighted yellow cells.