There are basically two formats of DVI
Format 1 is DVI analog - DVI-A
Format 2 is DVI digital - DVI-D
When the two formats are output, or input, by a single connector, then that connection is called DVI-A.
Basically, your DVI output on your computer carries BOTH analog and digital connectivity and can thereforce connect to EITHER a DVI-A monitor or a DVI-D monitor, or a DVI-I monitor - take your pick!
NOTE: DVI-A is (as far as I know) the exact same as a VGA connector, so no equipment has DVI-A, they just use a VGA connector on the monitor or device for VGA output.