Really stupid question, but going to put some coving up & plan to put the moulded corner pieces that go over the coving so dont have to miter. Anway i plan to buy the corner mouldings online, but have confused myself with what is an internal & external corner. A normal square room would have 4 internal corners? but if the room had a chimmeny breast, the chimmney breast pertruding into the room would have 2 external corners?