MCI_GENERIC_PARMS

typedef struct {
    DWORD  dwCallback;
} MCI_GENERIC_PARMS;

The MCI_GENERIC_PARMS structure contains the information for MCI command messages that have empty parameter lists. When assigning data to the members in this structure, set the corresponding MCI flags in the lParam1 parameter of mciSendCommand to validate the members.

dwCallback

The low-order word specifies a window handle used for the MCI_NOTIFY flag.