Wayne Barnes' forward pass formula is encrypted. He has a special criteria for working out whether a pass is legal.
Apart from a head-scratching ruling when Barnes over-ruled TMO George Ayoub and rubbed out a try to TJ Perenara, the English referee was solid. His luck was the forward pass decision did not decide the game.
In South Africa there was a more contentious ruling when French referee Mathieu Raynal ordered off Irish flanker CJ Stander for a high and late tackle when he leaped to charge down a kick from Patrick Lambie and in his follow through, clobbered the five eighths who was knocked out.
Both incidents highlight the difficulties for match officials and how systems need even more fine-tuning.