typedef enum _WHEA_ERROR_TYPE
{
         WheaErrTypeProcessor = 0,
         WheaErrTypeMemory = 1,
         WheaErrTypePCIExpress = 2,
         WheaErrTypeNMI = 3,
         WheaErrTypePCIXBus = 4,
         WheaErrTypePCIXDevice = 5
} WHEA_ERROR_TYPE;

Windows Vista Kernel Structures