COLLISION_GROUP_NONE  			= 0	--
COLLISION_GROUP_DEBRIS  		= 1	-- Collides with nothing but world and static stuff
COLLISION_GROUP_DEBRIS_TRIGGER  	= 2	-- Same as debris, but hits triggers
COLLISION_GROUP_INTERACTIVE_DEBRIS  	= 3	-- Collides with everything except other interactive debris or debris
COLLISION_GROUP_INTERACTIVE  		= 4	-- Collides with everything except interactive debris or debris
COLLISION_GROUP_PLAYER  		= 5	--
COLLISION_GROUP_BREAKABLE_GLASS  	= 6	--
COLLISION_GROUP_VEHICLE  		= 7	--
COLLISION_GROUP_PLAYER_MOVEMENT  	= 8	-- For HL2, same as Collision_Group_Player
COLLISION_GROUP_NPC  			= 9	-- Generic NPC group
COLLISION_GROUP_IN_VEHICLE  		= 10	-- for any entity inside a vehicle
COLLISION_GROUP_WEAPON  		= 11	-- Collides with everything but player - runs triggers
COLLISION_GROUP_VEHICLE_CLIP  		= 12	-- vehicle clip brush to restrict vehicle movement
COLLISION_GROUP_PROJECTILE  		= 13	-- Projectiles!
COLLISION_GROUP_DOOR_BLOCKER  		= 14	-- Blocks entities not permitted to get near moving doors
COLLISION_GROUP_PASSABLE_DOOR  		= 15	-- Doors that the player shouldn't collide with
COLLISION_GROUP_DISSOLVING  		= 16	-- Things that are dissolving are in this group
COLLISION_GROUP_PUSHAWAY  		= 17	-- Nonsolid on client and server, pushaway in player code
COLLISION_GROUP_NPC_ACTOR		= 18
COLLISION_GROUP_WORLD			= 19 	// Collide with only the world