Compartments

I want to use netsh to create a new routing compartment, assign a couple of
existing interfaces to it, and manage its routing table.

"show compartment" tells me a little but not much. "set compartment" is
limited. There's no "add compartment".

Coming at it via "set" on "interface" or "route" doesn't seem to touch
compartment stuff ...

So, like, how *do* you partition off a couple of physical Ethernet
interfaces into their own "routing compartment"?