it is very much like an invitation to a wedding in the West, except that at some place on the card it will say, "The ordinand requests your forgiveness of any offence by thought, word, or deed that he may have committed." with a polite wai he will extend this card to you, holding it between his hands. You accept it and can say, "Of course, you're forgiven or"There was nothing to forgive Or you can merely smile and say, "Thank you." A fairly strict Buddhist may say, "Kho anumodana," which is a very formal way of saying thanks for the chance he has given you to help him, and thus make merit in your own life. It is the same situation discussed earlier: when you offer food to the monk in the morning, he will never thank you, for he has given you a chance to practice dana("generosity"), one of the Buddhist's virtuous acts, and thus to make merit.