In this Washington Post 6-star, a 9-wing turns up on the third marked line, banning 9 candidates in two columns if five unmarked lines, and on the eighth marked line, a naked triple and resulting naked pair eliminate 5 candidates in c6. With line slinks, so marked, X-wings are easy to spot.
The naked pair creates a second 9-wing, which is marked to ban 9’s in unmarked r5, and three marked lines later, a naked pair in r7 brings SE8 and a naked single without searching effort, S5, and the collapse on the line marking trace follows.
The line marking trace combines exact reporting of the line marking order, advanced techniques like the X-wing and naked single, and the follow up detail seen in the bypass.
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Systematic Sudoku 