Nil Recurring (also Transmission 5.1) is an EP by British progressive rock band Porcupine Tree, released on 17 September 2007 through the band's online store. The standard version of the mini-album is composed of four tracks written during the "Fear of a Blank Planet" recording sessions and was completed over the summer of 2007. The EP's title, which stems from the opening instrumental track on the EP, was actually derived from an unreleased demo written during the "Fear of a Blank Planet" recording sessions, called "Always Recurring". Although the band never formally released the song, lyrical and melodic elements of the track were reused in the closing piece of the EP, "What Happens Now?".