Normal sudoku rules apply. Digits along grey lines will read the same when you roll out the grey line along the row or column, e.g. the line in box 1 would 'unroll' along column 1 and would read the same down column 1 as it does r1c1 to r2c2.
Normal sudoku rules apply. Digits along grey lines will read the same when you roll out the grey line along the row or column, e.g. the line in box 1 would 'unroll' along column 1 and would read the same down column 1 as it does r1c1 to r2c2.