[bellnier]

In rugby we take the advantage-disadvantage principle to extreme...for example, if defense (white) commits an infraction against offense (black), offense is allowed to continue play until the official deems that any advantage they may have had before the penalty was reversed by the defensive players mistake. Retention of advantage may be yardage gained, completion of pass(es), etc. and can be somewhat subjective. If no advantage is lost, then no whistle. Official announces on field 'advantage black' when the infraction is commited. The announcement is not always heard from the sidelines so to the typical observer this indeed looks like a 'rule-less' game, but in fact this concept ensures good game flow with very few interruptions.