DDM Floor Rules
If you play in a home environment, you don't need this document. But once you start playing in official DCI tournaments, you are expected to follow the rules that are set forth in the DDM Floor Rules.
For the lazy people we've made this executive summary of the Floor Rules:
Players are expected to behave in a respectful and sporting manner at all times. Players shall abide by all rulings, including penalty rulings of the judge of duty. Players are required to have DCI number.
Judges are in place to insure that the tournament runs smooth. Players are expected to ask for a judge when they are unsure of a rules question, but also when they see unsporting behaviour of their opponent.