For questions about Magic: The Gathering's Professional REL (Rules Enforcement Level), its highest REL. Used at Grand Prix Day 2, Pro Tour, and the World Magic Cup.
The Professional Rules Enforcement Level (REL) for Magic: the Gathering is the highest level of rules enforcement used for most Magic tournaments, including Grand Prix Day 2s and Pro Tours. This REL expects players to have a very good knowledge of game rules and tournament procedures and has stricter rules enforcement than Regular or Compettitive REL. The official definition can be found in the Magic: the Gathering Tournament Rules.
Not all Magic: the Gathering questions need a Rules Enforcement Level tag. Questions using this tag should be about how tournament or other high-level Magic play under the Professional REL affects the various parts of the game, especially judge rulings and player interactions.