logic_proximity

This entity is not in the FGD by default.
It should not be put directly in a map because it's useless.

Class hierarchy
CPointEntity ↳CBaseEntity
triggers.cpp

logic_proximity is an entity available in all Source games. It's tied to CPointEntity but doesnt't have any other code that would do something with it. Use trigger_proximity or point_proximity_sensor instead of this entity.