INT 2F - MS WINDOWS - VIRTUAL DEVICE CALL OUT API
AX = 1607h
BX = virtual device ID (see INT 2F/AX=1684h)
CX = (usually) callout subfunction
Return: (usually) AX,BX,CX,DX,ES contain results
Notes:  more of a convention than an API, this call specifies a standard
mechanism for Windows enhanced-mode virtual devices (VxD's) to talk
to DOS device drivers and TSRs
see below for details on several virtual devices
SeeAlso: AX=1605h,AX=1607h/BX=000Ch,AX=1607h/BX=0014h

See also: 2F0C20

2F1607 - MS WINDOWS - VIRTUAL DEVICE CALL OUT API