Port Types Port types found in certain DWDM cards are described in the following table. Port Type Description LINE-RX Input Line LINE-TX Output Line COM-RX Input COM COM-TX Output COM EXP-RX Input Express EXP-TX Output Express CHAN-TX Drop CHAN-RX Add OSC-TX Input OSC OSC-RX Output OSC ADD-RX Add DROP-TX Drop PASS-THROUGH Pass-through