VPAP III ST-A vs. VPAP III ST

Does anyone know the difference between these two machines? Someone kindly gave me the link to the clinicians manual to the III ST, but the machines aren't exactly alike. For Example the ST is supposed to give AI and AHI data, the ST-A does not. The regular ST clinicians (the one I downloaded)
manual is the one my DME seemed to have. She was not at all familiar with the machine. I don't know if AI and AHI are available via software or not. Still waiting for my cable in the mail....

Thanks,
Mary Z.

crossposted to SleepGuide