Etoimos I have the ZWO ASI2600MM and the documentation for it says that it supports ROI, but I can't find anything in the ASIAIR Plus about ROI.
All CMOS cameras support user specified ROI (just check their SDK).
Except for the Live mode, ASIAIR just does not expose the ROI functionality to the user (just as it keeps the user in the dark for countless other non-beginner functions).
The only exception is the ASI6200, where the APS-C ROI is available.
Chen