Serial port, equivalent of "full duplex" flow control?

I have a document with connection information to a device over a serial port. It specifies "full duplex" as the setting for flow control. Under Windows, I have the following options for setting up the flow control:

• Xon/Xoff
• Hardware
• None

What is the equivalent of "full duplex" in the above list?

From stackoverflow

• "xon/xoff" is a synonym of "software flow control" (as opposed to "hardware flow control").

  "full duplex" means "in both directions"; theoretically you can enable software flow control or hardware flow control in one direction only (i.e. "half duplex"), or in both directions ("full duplex") ... so there's not enough information to answer the question.

  What kind of device is it? If I had to guess, my first guess would be "hardware" flow control, simply because "software flow control" is less compatible than "hardware flow control" with transferring binary data.

  unforgiven3 : It's an X-ray generator :-) - I'll try hardware flow control, thanks!

  ChrisW : Yikes! Maybe you should read the manual again, or call tech support ... or perhaps there's some official training in how to use this device.

  unforgiven3 : Haha, fortunately I don't need to do that, I understand now - I actually can get away with "None" for flow control, and it works, but your answer cleared up what "full duplex" meant for me. Thanks!