typedef enum _PNP_VETO_TYPE
{
         PNP_VetoTypeUnknown = 0,
         PNP_VetoLegacyDevice = 1,
         PNP_VetoPendingClose = 2,
         PNP_VetoWindowsApp = 3,
         PNP_VetoWindowsService = 4,
         PNP_VetoOutstandingOpen = 5,
         PNP_VetoDevice = 6,
         PNP_VetoDriver = 7,
         PNP_VetoIllegalDeviceRequest = 8,
         PNP_VetoInsufficientPower = 9,
         PNP_VetoNonDisableable = 10,
         PNP_VetoLegacyDriver = 11,
         PNP_VetoInsufficientRights = 12
} PNP_VETO_TYPE;

Windows Vista Kernel Structures