Port Types Port types for 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 EAD Express add drop AD Add drop port