struct HEAP_STOP_ON_TAG

typedef struct _HEAP_STOP_ON_TAG
{
     union
     {
          ULONG HeapAndTagIndex;
          struct
          {
               WORD TagIndex;
               WORD HeapIndex;
          };
     };
} HEAP_STOP_ON_TAG, *PHEAP_STOP_ON_TAG;

Windows Vista Kernel Structures