The two black labeled PT ports are just 8 copper wires between the back of the AP and the bottom of the AP. They are not connected to the internal circuitry of the the AP, and for that reason can be used for anything that would run over a 4, 6 or 8 wire RJxx connector.
So that can be another PoE+ ethernet, serial port, analog phone. Example: when used as a remote-AP, the E0 is connected with a short cable to the PT on the back of the 205H, which wires the E0 to the black port on the bottom. That makes that you can use the port on the bottom to connect the AP.
Does this answer your question??