Tournament participants must provide their DCI membership number to the Scorekeeper during registration.
The DCI number also helps keeps tabs on what events people play in for Planeswalker Points, and helps uniquely identify players in an event where multiple people can have the same name.
Players without a DCI membership number must request one from the Tournament Organizer. There is no cost associated with joining the DCI, but members are only allowed one DCI membership number.
If a player ends up with more than one DCI number, they can merge memberships online. Nevertheless, players may not intentionally maintain multiple memberships (e.g., in order to play while their main number is suspended). Players are also required to use their real names, that they use in real life. Their registered names don’t have to be their full legal names; a player may register as “Mike” instead of Michael but can’t register as “Roflcopter McGee.” The registered name should be what the player identifies as their name.
Results containing temporary player numbers, temporary player names, or placeholders may not be reported to the DCI.
Some Tournament Organizers may add a fake player in order to sanction an event with 7 players. This is strictly prohibited. If only 7 people show up for an event, players can still play, but the event must be run as an unsanctioned event. See MTR 10.1 for more information on participation minimums.