typedef struct _CM_KCB_UOW
{
     LIST_ENTRY TransactionListEntry;
     PCM_INTENT_LOCK KCBLock;
     PCM_INTENT_LOCK KeyLock;
     LIST_ENTRY KCBListEntry;
     PCM_KEY_CONTROL_BLOCK KeyControlBlock;
     PCM_TRANS Transaction;
     ULONG UoWState;
     UoWActionType ActionType;
     HSTORAGE_TYPE StorageType;
     union
     {
          PCM_KEY_CONTROL_BLOCK ChildKCB;
          ULONG VolatileKeyCell;
          struct
          {
               ULONG OldValueCell;
               ULONG NewValueCell;
          };
          ULONG UserFlags;
          LARGE_INTEGER LastWriteTime;
          ULONG TxSecurityCell;
          struct
          {
               PCM_KEY_CONTROL_BLOCK OldChildKCB;
               PCM_KEY_CONTROL_BLOCK NewChildKCB;
          };
          struct
          {
               PCM_KEY_CONTROL_BLOCK OtherChildKCB;
               ULONG ThisVolatileKeyCell;
          };
     };
} CM_KCB_UOW, *PCM_KCB_UOW;

Windows Vista Kernel Structures