Make my corrections! Please!
Well-known mandatory : These PAs must be recognized by all BGP routers and passed along to other peers.
Well-known discretionary : These PAs do not need to be in every update, but they must be recognized by all BGP routers.
Optional transitive : These PAs don’t have to be recognized but they must be passed along to other BGP peers if they are present in an update.
Optional notransitive : These PAs neither have to be recognized nor passed along.