Normal sudoku rules apply. Each circle has a value equal to the four digits around the clue arranged in ascending order. Eg if the four digits were 4,3,6,4 then the value of the circle would be 3446. Assign each circle a rank according to its value's position in a list of the all of the circles' values. The lowest rank would have rank 1, the next lowest would have rank 2 etc. Place each circle's rank into the cell at the tip of the arrow emerging from that circle. NB clues with the same value would have the same rank and would have the same digit in the tip of their circle's arrow. Digits in a cage sum to the given total.