From The TV IV
A construction permit is issued to a TV station by the Federal Communications Commission when said station wishes to modify its broadcasting status. A construction permit is issued for the following requests:
- A request to increase/decrease the station's power.
- A request to change the station's city of license.
- A request to change the station's broadcasting frequency.
- A request to move the station's transmitter to another location.
Construction permits are assigned by auction. In the past, permits were given based on what station's programming would serve the city of license the best.