Allows a protected-mode OS/2 session to communicate with a virtual device driver (VDD).

#define INCL_DOSMVDM
#include <os2.h>

HVDD      hvdd;      /*  The handle of a VDD returned by a previous call to DosOpenVDD. */
SGID      sgid;      /*  The identifier of a specific DOS session, or null. */
ULONG     cmd;       /*  A function code that is specific to a virtual device. */
ULONG     cbInput;   /*  The length, in bytes, of the application data in pInput. */
PVOID     pInput;    /*  The address of the command-specific information. */
ULONG     cbOutput;  /*  The length, in bytes, of pOutput. */
PVOID     pOutput;   /*  The address of the buffer where the VDD returns the information for the specified command. */
APIRET    ulrc;      /*  Return Code. */

ulrc = DosRequestVDD(hvdd, sgid, cmd, cbInput,
         pInput, cbOutput, pOutput);