Michael had a curious question. "What is an escutcheon plate, and what is it used for?"
An escutcheon plate is similar to a face plate, although usually round. Its function is to cover the hole which something is inserted through. So those decorative plates in the shower that go around the faucet stem, under the faucet handle, are escutcheon plates. That decorative and sometimes burglar-proof ring that goes under the door lock to cover the hole is an escutcheon plate.
I knew what it was, but I have to admit that it took us a while to figure out how to spell it.