He cannot see beyond his own nose. This definition is one of the most important rules of play, because it decides what the player is allowed to refer to. The 'enclosure' of the player is usually the current location. On the other hand, a player who puts the lamp on the ground and turns it off then loses the ability to turn it back on again, because it is out of scope.
Compass directions make sense as things.
The parser applies scope rules to all actors, not just the player. The concealed attribute only hides objects from room descriptions, and doesn't remove them from scope. Two library routines are provided to enable you to see what's in scope and what isn't. Formally, scope determines what you can talk about, which usually means what you can see. Suppose a locked chest is inside a sealed glass cabinet.