typedef struct _OBJECT_HEADER
{
     LONG PointerCount;
     union
     {
          LONG HandleCount;
          PVOID NextToFree;
     };
     POBJECT_TYPE Type;
     UCHAR NameInfoOffset;
     UCHAR HandleInfoOffset;
     UCHAR QuotaInfoOffset;
     UCHAR Flags;
     union
     {
          POBJECT_CREATE_INFORMATION ObjectCreateInfo;
          PVOID QuotaBlockCharged;
     };
     PVOID SecurityDescriptor;
     QUAD Body;
} OBJECT_HEADER, *POBJECT_HEADER;

Windows Vista Kernel Structures