[TenTec] Orion II Screen VFO "A" and "B"

[K5XS at aol.com]

I've had my Orion II for two days now and am very much enjoying it.
 
I've been playing around with the VFOs anf the dual receivers, and can't  
seem to figure out why the "A" (to the immediate left of the A VFO frequency) is  
in reverse (a dark block around a white "A"), while the "B" next to the B VFO 
 frequency is a dark letter with no block.  Does that indicate I have  
something is set to "A"?  I have played around with the buttons selecting  both VFOs 
driving both receivers in all combinations, and it stays the  same.  (Is it 
just another way of distinguishing between the two VFOs  on the screen?)  
 
Thanks for thoughts.
 
Bernie K5XS