Blank (unexposed) motion picture film attached to the beginning or end of a reel of film, usually used for threading a playback machine, and which contains information about the reel’s content such as film title, reel number, etc. as well as the count-down section. Opaque leader is used in A – and B roll B – Rolls, in editing workprints and film soundtracks, to fill spaces between specific sound effects or musical segments, or to fill in for picture or sound segments to be added later. See also Academy leader, SMPTE Universal leader, plastic leader, fill leader.