The document discusses the various codes and conventions used in film opening sequences. It identifies elements like establishing the genre, introducing characters, setting the theme and mood, using narration, sound, enigmas, credits, flashbacks and establishing shots. The purpose is to draw the audience in and set expectations for the film by revealing its tone and genre from the very start. Common techniques include positioning characters in genre-specific situations, enticing the audience with unanswered questions, and using animation, music and visuals to immerse viewers.