The document discusses four types of opening title sequences (OTS): linear, non-linear, symbolic, and linear (part 2) and non-linear (part 2). Linear OTS present information in chronological order to introduce the story and main characters, such as in Forrest Gump and Anchorman. Non-linear OTS use montage editing and do not directly introduce characters, shown in Seven and The Walking Dead. Symbolic OTS rarely include film footage and instead use visuals to represent themes, like the ink in The Girl with the Dragon Tattoo and the imagery in Skyfall.