Normal sudoku rules apply. Every 3x3 box contains an invisible 'index line' whose route must be determined. The index lines are all 9 cells long, only move orthogonally (not diagonally), and don't cross any 3x3 box borders. They don't cross themselves, or pass through any black or green spots. Each row, column and box contains exactly one hidden diamond, which lies at one end of its index line, and contains its box number. (Boxes are numbered 1-9 in normal reading order from top left to bottom right.) The digit in position N along an index line (starting at the end with the diamond) indicates the position along the line where the digit N should be placed. Eg: if the 1st digit is a 3, then the 3rd digit will be a 1. Digits separated by a black spot are in a 1:2 ratio (ie one digit will be double the other). Digits separated by a green spot have a difference of at least 5.