While we all wait for Valve to release the big Left 4 Dead-Left 4 Dead 2 crossover expansion pack, the game's official blog site is giving all of us an education in the specific terms that Valve has created to describe certain things in the zombie co-op shooter. For example, "Masking" doesn't mean what players do when they see blood splatter but describes an environment where players can walk and shoot inside but can't see through.

Similarly, a Holdout is not a team member that refuses to play as part of the team but is a part of a game level where survivors have to gather at the end of a mission and defend against the final zombie horde. And you thought your education was over.