Identifies a physical runway at an airport.
For example, at Arlanda there are 3 Physical Runways: 
Each physical runway can be divided into Logical Runways.  At Arlanda there are 2 for each Physical Runway:
- RWY1: 01L and 19R
- RWY2: 8 and 26
- RWY3: 01R and 19L