INT 21 U - OS/2 v2.0 - "DosOpen2"
        AX = 6C01h
        ???
Return: ???
Note:   this function is similar to AX=6C00h, but supports OS/2's extended
          attributes
SeeAlso: AX=5704h,AX=6C00h,AH=6Fh"OS/2"

.