[Elecraft] [K3] clarification on VFO and 2nd Rx

[Barry N1EU]

I'm unclear about VFOA/B functionality when using the main and
subreceiver in diversity mode (i.e., tuned to same frequency) and the
transmitter in split mode.  It seems that the subrx needs to be
assigned to VFOA in this case but I'm not sure if the K3 provides that
flexibility (like the Orion).  The manual attempts to address this
specific case as follows, although I'm not getting it:

"Split Mode with the Sub receiver: When operating split, VFO A is the
receive frequency and VFO B the transmit frequency. If the sub
receiver is on, you'll be able to listen to both your receive and
transmit frequencies in receive mode. Hold SPLIT to turn split mode on
or off."

Can someone explain what the manual is trying to say here and how
VFOA/B is being assigned to the subrx in diversity/split?  Is the
subrx always assigned to VFOB or is there more flexibility than this?

Thanks & 73,
Barry N1EU