Wizards of the Coast have announced that they're updating how their system deals with people's DCI numbers, the number that players give to tournament organizers and shops when they play in Magic: The Gathering tournaments.
The update will mostly affect players who have DCI numbers but don't know them. "Your play history and DCI number will be unaffected regardless—we are not deleting any DCI numbers or play histories from our system."
The change in the database may cause some issues to players who didn't memorize their DCI numbers memorized, but may want to use DCI to join Magic: The Gathering sanctioned events. Wizards reminded players who plan to attend Grand Prix or other sanctioned events to memorize their DCI numbers because after March 21, organizers won't be able to look up your DCI numbers in the system. This is probably to secure DCI accounts from being used by players who don't own them.
Wizards summed up some steps on what to do for those who know their DCI accounts and for those who don't:
If you know your DCI number:
You may continue to use your DCI number for most events, even without having a Wizards Account.
We do, however, recommend you go to accounts.wizards.com to either activate a Wizards Account or to make sure that it is linked to your preferred DCI number. If you have any trouble, contact customer service.
If you don't know your DCI number but would like to retrieve it, or think you may want to access your organized play history in the future:
If you already have signed up for a Wizards Account, a tournament organizer—including at your local store—can look up your DCI number associated with your account.
If you already have signed up for a Wizards Account, you can see your DCI number on your profile page after logging in at accounts.wizards.com. You can even save an image of your DCI card to your phone from your profile page.
If that is not an option, you can contact customer service to help retrieve your DCI number and add it to your Wizards Account.
If you're a tournament organizer or Wizards Play Network retailer:
You will be required to have a Wizards Account. If you do not already, you can contact customer service.
If any of this applies to you, please make sure to have your account created or updated by March 21. If you need to contact customer support, you can do it one of these ways:
If you have a Wizards Account, you can contact customer service through wizards.custhelp.com.
If you do not have a Wizards Account, you can create one at accounts.wizards.com, and then use online help at wizards.custhelp.com.
This change may cause some issues in the short-term, but I think it will benefit a lot of players and help make their DCI numbers more secured.
Source: Wizards of the Coast