The Green Card:

Rewarding Sportsmanlike Conduct

When both linesman give no indication,

the ref doesn't see a touch, and a player admits a touch against their own team. The point goes the other way, and a green card and a clap is awarded

The linesman on Team B isn't sure, the ref is 80% sure the ball was out on team B's side, but Team B's players call it in. The point goes to Team A and Team B receives a clap and a green card

When a captain brought an incorrect score to the referee's attention, a point for the other team had been missed. That captain received a clap and a green card.