Starfleet Directive 244 was a directive restricting the space around the Delphi Ardu star system and especially the planet Delphi Ardu IV.
After the USS Enterprise encountered Portal 63 and the remnants of the Tkon Empire in the year 2364 (TNG episode: "The Last Outpost"), Starfleet Tactical gathered a task force to develop strategies on how to deal with the Tkon and their supremely advanced technology. As no other Tkon had been encountered outside the Delphi Ardu system, the decision was made to keep traffic away and allow entry only by permission from the Federation Council. (ST video game: Resurgence)