[Hallicrafters] Off-subject question for old-timers

[Waldo Magnuson]

On some early (late 1940's and 1950's) FM radios (mostly Zenith) there 
is a dot on the dial near 100 MHz.  Several suggestions have been:
1. Zenith had their own FM broadcast station on their plant site at 
99.0 MHz.
2. It's an emergency frequency.
3. It's where the Zenith repairman put the dial to find tune the radio.
4. It's 1/2 way on the FM dial.
Does anyone know the real answer?
Thanks.  Skip Magnuson