Each episode of Star Trek includes the captain's log. Each episode of Bones ends with a sweet moment between Booth and Brennan. Most episodes of Criminal Minds are bookended with quotes that are relevant to that episode.
Some TV series are written by a writing team, and others accept script submissions. As far as I know, all shows have a "bible." Is there a specific term for those elements that must be in a TV episode? If there is, what is it?