Sector 21538 was a region of space. In 2369, a starship mission status listed the activity of Federation starships in sectors 21538 to 23079. This chart was seen in the observation lounge of the USS Enterprise-D. (TNG: "Chain of Command, Part I" , display graphic) This sector was only mentioned in writing. Sector 21538 was not mentioned on screen, but rather was seen on a viewscreen chart on observation lounge. It was also displayed on a PADD, as shown in the It's A Wrap! sale and auction. [1]