This structure contains fields for the MCI_GROUP message.
typedef struct _MCI_GROUP_PARMS { HWND hwndCallback; /* Window handle. */ USHORT usGroupID; /* Group ID returned. */ USHORT usReserved0; /* Reserved. */ ULONG ulStructLength; /* Length of structure. */ USHORT usMasterID; /* ID of master device. */ USHORT usReserved1; /* Reserved. */ PSZ pszGroupAlias; /* Alias name. */ ULONG ulNumDevices; /* Number of devices in group. */ PULONG paulDeviceID; /* Device IDs in the group. */ } MCI_GROUP_PARMS; typedef MCI _ GROUP _ PARMS * PMCI _ GROUP _ PARMS ;