Reject?

[DOOMinator]

What the hell is a "reject" exactly? And a "reject map builder?"

[The Ultimate DooMer]

Reject is a set of data tables that calculates LOS (line of sight) for the sectors in each map, and is required when you want to build a new map (although you can avoid using it until you place monsters in order to save time). Without it, the monsters won't see you until you enter their sector. A reject builder builds the reject tables, although many nodebuilders do this as well.