3-cell Kakuro run summing to 8

Only 2 digit sets sum to 8 across 3 cells. That makes this run useful for cross-reference deductions: a digit you can rule out from one of the cells (because the perpendicular run forbids it) often forces the entire combination.

Locked digits: 1. This digit appears in every valid combination, so it must occupy one cell of the run; useful when a perpendicular run rules it out of a candidate cell.