Not sure how much VRV/VRF system types you folk in the states are
seeing. One particular system type we have installed a fare bit of is
the Mitsubishi 2-Pipe Simultaneous Heat/Cool Energy Recovery.
The Flash Presentation on the page has a drop-down menu to the top
left of the image. You can use the menu to flick through and see the 3
typical modes and some charge checking info.
Basically, during majority cooling, you will have a saturated mixture
of liquid and vapour traveling to the indoor BC Box where the liquid
is then gravity separated for feed to cooling units and the vapour
then off the top of the separator goes to the heating units.