My program doesn't have bugs. It just develops random features.

From Unreal Wiki, The Unreal Engine Documentation Site

Object >> Actor >> Brush >> Volume >> PhysicsVolume >> DefaultPhysicsVolume

Package: 

Engine

This class in other games:

U2, U2XMP, UDK, UE2Runtime, UT2003, UT2004

The default physics volume for areas of the level with not contained in any mapper-placed physics volume. This class should never be spawned or destroyed by UnrealScript code. Exactly one instance of this class is created at level startup to ensure the Actor.PhysicsVolume property always contains a value other than None.

[edit] Default values

[edit] Subobjects

[edit] BrushComponent0

Class: Engine.BrushComponent

Inherits from: PhysicsVolume.BrushComponent0

No new values.

[edit] Events

[edit] Destroyed

Overrides: Actor.Destroyed

Crashes the game on purpose. The DefaultPhysicsVolume must not be destroyed during the game.