path_corner
path_corner is a point entity available in all 
GoldSrc games. Multiple path_corners form a path that can be followed by various moving entities.
Clarify:
func_tracktrain and func_vehicle use path_track; most other entities use path_corner. Key Values
Targetname:
- Name
(targetname)<string> - The targetname that other entities refer to this entity by.
- Pitch Yaw Roll (Y Z X)
(angles)<angle> - This entity's orientation in the world. Pitch is rotation around the Y axis, yaw is the rotation around the Z axis, roll is the rotation around the X axis.
- Next stop target
(target)<targetname> - Name of the next path_corner in the path.
- Fire On Pass
(message)<targetname> - Trigger an event when this path_corner is passed by the entity using the path.
- Wait here (secs)
(wait)<integer> - Wait for this number of seconds before moving to next corner.
- New Train Speed
(speed)<integer> - Speed of the train once it passes this path_corner.
- New Train rot. Speed
(yaw_speed)<integer>
Flags
Wait for retrigger : [1]
- Moving entity will wait and will only continue when triggered.
Teleport : [2]
- Makes a func_train entity teleport to the current path_corner.
Fire once : [4]
- Will only fire its Fire On Pass" target once.
