INT 21 - DOS 3.1+ - IOCTL - CHECK IF BLOCK DEVICE REMOTE
AX = 4409h
BL = drive number (00h = default, 01h = A:, etc)
Return: CF clear if successful
DX = device attribute word
bit 15: drive is SUBSTituted
bit 12: drive is remote
bit  9: direct I/O not allowed
CF set on error
AX = error code (01h,0Fh) (see AH=59h)
Note:   on local drives, DX bits not listed above are the attribute word from
the device driver header (see AH=52h); for remote drives, the other
bits appear to be undefined
SeeAlso: AX=4408h,AX=440Ah,INT 2F/AX=122Bh

See also: 214400

214409 - DOS 3.1+ - IOCTL - CHECK IF BLOCK DEVICE REMOTE