AS Functions of a opening sequence

The functions

The function of an opening title sequence to a film is to establish the visual style of the film and to introduce the viewer to all or some of the following:
Characters
Location
Narrative/Plot
Genre
Themes

The Elements

Typically, an opening sequence will contain:
Details of cast and crew.
The film's title.
An introduction to character or character type.
Indication of place.
Indication of historical period.
Information regarding mood and tone.
Introduction to signature theme tune.
Information about genre.
Questions that the viewer finds intriguing.
Patterns and types of editing that will be echoed in the remainder of the film.
Mise en scene and cinematography that will be echoed or elaborated upon later in the film