What is the author's style in Foucault's Pendulum by Umberto Eco?

The story is told from the point of view of the main character, Casaubon. The novel begins with Casaubon in a museum in Paris, attempting to find his friend Belbo. Most of the novel is composed of flashbacks from the point of view of Casaubon while he waits for a meeting with Belbo's kidnappers in the Parisian museum. Much of the novel involves Casaubon reading from Belbo's computer files and then reminiscing about the events related to the files. This leads to flashbacks within flashbacks that tell the story of Casaubon's life and the details of the events that culminate in Casaubon's search for Belbo in the museum.

Since most of the novel is either flashback or Casaubon thinking about an event in the past, the narrator has some knowledge of the future, but only the future he directly experiences. He is reliable up to an extent, but it is important for the reader to always remember that Casaubon is never in possession of all the relevant facts and his views about the psychology and motivations of others are really only speculations. There is a great deal of foreshadowing in the narration because the narrator knows that certain events will ultimately lead to the unhappy fate of having to track down a kidnapped friend after hours in a Parisian museum. Once the narration picks up with Casaubon in the museum, the narrator becomes more tentative and provisional, presumably because he does not know what is going to happen. After the murder of Belbo, the point of view becomes almost totally reflective and focuses on Casaubon's thought and reflections about the events of the novel and their meaning.