enum CONFIGURATION_CLASS

typedef enum _CONFIGURATION_CLASS
{
         SystemClass = 0,
         ProcessorClass = 1,
         CacheClass = 2,
         AdapterClass = 3,
         ControllerClass = 4,
         PeripheralClass = 5,
         MemoryClass = 6,
         MaximumClass = 7
} CONFIGURATION_CLASS;

Windows Vista Kernel Structures