I've heard this idea called different things, but I prefer point of entry. It is similar to point of view in literature. In a screenplay point of view (pov) usually refers to a camera angle. For example, if a father is looking down at his daughter you could do a "reverse pov" and suddenly the camera is looking up at dad from the daughter's perspective.
(btw - you are NOT writing camera angles in your spec script. Do not, do not, do not. Your job is action/dialogue - i.e. moving the story forward. Camera angles are decided by director and DOP and added to the shooting script.)
POINT OF ENTRY means how we, as the audience, enter the story. For instance, if you have ONE point of entry, you have one perspective, usually the protagonist's (similar to 1st person limited in literature). This means the audience ONLY knows what the protagonist knows. We see what she sees, we hear what she hears. If someone leaves the room, building, car, etc, we do not follow that person. They are off camera.
This "point of entry" person would be in EVERY scene. Adhering to this technique creates mystery, because we experience the story as the protagonist does. We learn as she learns.
The other side of the spectrum is unlimited points of entry (like omniscient POV in fiction). It means we can see anything happening anywhere around the world from an perspective, including when no one is around (i.e. a shipwreck underwater). This works better in some genres. In horror films we often jump from perspective to perspective as the victims are killed off. In science fiction we might see a spaceship flying past a planet and then landing on another. In Lord of the Rings sometimes we were with Frodo, sometimes with Elrond, sometimes with Gandalf... you see where I'm going with this.
Ensemble casts usually have multiple, but limited, points of entry. We usually only see what the core characters see and not just any old character in the film. In Breakfast Club, for example, we could be with the principal or any of the students, but we never saw anything from the parents' perspectives.
Some people believe that it is best to stick with the LEAST amount of entry points possible, to avoid confusion, which is a difficult task. I think it really depends upon the genre and story and how you want to reveal information. It's something you should definitely consider.
My script Brigitta of the White Forest has only ONE point of entry. Brigitta's. She is in every scene and we only see what she sees. If she doesn't witness it, neither do we.
I recently decided to change Howler from one point of entry to TWO points of entry, that of the protagonist and that of the antagonist. This means that one of these two characters must be in every scene. I decided that I wanted to reveal some information to the audience that Howler doesn't know. Having your audience know something your protagonist doesn't can create another kind of tension (eek - don't go into the house, the bad dude is waiting for you in there!).
I believe HOW information is revealed is key to creating a good mystery and story. Being conscious of how many points of entry your screenplay has, and making a conscious decision to write it a particular way, will only serve to improve your writing. Your story can become confusing, and your audience might lose interest in your protagonist, if there are too many points of entry.
If you want to read more about this, I found an article about Point of View in Screenwriting by David Terusso.