Zipper Lines

What is the Zipper Lines rule?

Zipper Lines is a variant sudoku rule: digits at equal distances from the centre of the line must sum to the same total (the 'zipper sum'). Different zipper lines may have different sums.

In every puzzle here the setter’s own rules text is shown beside the board, so the exact wording for the puzzle you are solving is always one glance away. All normal sudoku rules apply unless the setter says otherwise.