Structure of film openings.

There are 3 basic structures of film openings; narrative, discrete and stand alone.

Narrative: the first part of the film is seen with titles either superimposed or intercut.
Films such as Law Abiding Citizen and Panic Room use this type of opening. Titles are superimposed, there are series of shots linked to narrative and the title sequence leads directly into film.

Discrete: shots/images/scenes that stand apart from the film with titles. It may contain elements from the films that could suggest the plot or genre, nut they are not part of the narrative.
Films such as Enemy Of The State and Se7en use this type of opening. There are a series of shots that are not linked to narrative, titles are superimposed and there is some stylised editing and special effects.

Stand alone: the title sequence is on its own and leads directly into the film.
Films such as Donnie Darko and The 39 Steps use this type of opening. Titles are alone, not combined with shots/scenes. There is no indicator of the plot/genre and the titles lead directly into narrative.

Another structure of film openings is 'stylized editing'. This is a more complex style where there is a lot more editing in comparison to the other structures.
The Taking Of Pelham 123 uses this type of opening. The editing is fast paced and indicates the genre of the film. Titles are superimposed and leads straight into narrative. The titles are on the same beat as the music in the background. There is also an indication of the plot of the film.