[Elecraft] What is t-r 8r mode ?

[w2bvh]

I don't understand what the t-r menu's 8r hold/nor parameter is.  Can 
someone explain the difference between "nor" and  "hold" values and what 
that will to for my newly built XV50 (and for regular operation without 
the XV50)? Will this parameter impact QSK in a negative way?

And while we're at it. There is a warning in the XV manual about having 
a hf antenna connected to the second antenna port of my KAT2 while using 
the XV on the other antenna port. Is th isolation really that poor that 
I would be transmitting a readable signal on 10 meters while using the 
XV50 ????

Thanks in advance for your advice and Happy New Year to all!

73,
Lenny W2BVH