Possible values of an option:
[Half], [Full] and, probably, [N/A]
[Half Duplex], [Full Duplex] and, probably, [N/A]
The option description:
This option is accessible only when COM2 functions as infrared port. She allows to install a mode of its operation: half duplex ([Half] or [Half Duplex]), used by default, or full-duplex ([Full] or [Full Duplex]), supported, alas, not all exterior devices. Value [N/A] if it is present, says that the infrared port is disconnected.
The half duplex assumes that at once time date transmission can go only in one direction (we tell, only from the computer to a mobile phone or, on the contrary, only from a mobile phone to the computer). The full-duplex mode allows to exchange the data simultaneously in both directions. As you, probably, guess, from the point of view of speed the second variant is more preferable.
Other options identical to destination: