Normal Sudoku rules apply. Clues are given on selected diagonals in the format T [S]: - T is the total sum of the digits along the diagonal; - S is the sum of the digits on the diagonal that are located between the highest and lowest digit present on that diagonal (but excluding those two digits); - If S is given as a number (0 or greater), there is a unique highest digit and a unique lowest digit on the diagonal; - If S is given as “-“, the sandwich sum is undefined, because the highest digit or the lowest digit (or both) repeat along the diagonal; - sometimes the T clue is omitted and only the [S] part given.