This is an example of a completed Palindrome Line Sudoku. All the usual rules of Sudoku apply, but the grid also contains Palindrome lines.
            
            
                The digits along a Palindrome Line must read the same in both directions.
            
            
                If you look at the line in the top-right of this puzzle, the digits read 47874, this is the same backwards and forwards.
            
            
                This is the case for all lines in this puzzle.