Normal sudoku rules apply. Cells separated by dots have the same common difference (green for one difference; red for another). Outer clues are grouped in pairs; in each pair, one clue is a sandwich clue and the other is an x-sums clue. A sandwich clue gives the sum of the cells sandwiched between the 1 and 9 in that row/column. An x-sums clue gives the sum of the first X digits placed in the corresponding direction, where X is equal to the first digit placed in that direction. Some outside clues use dots in their equations: these are multiplication or "to the power of", not concatenation. Not all possible clues are given IE no negative constraints operate.