struct RTL_TRACE_BLOCK

typedef struct _RTL_TRACE_BLOCK
{
     ULONG Magic;
     ULONG Count;
     ULONG Size;
     ULONG UserCount;
     ULONG UserSize;
     PVOID UserContext;
     PRTL_TRACE_BLOCK Next;
     VOID * * Trace;
} RTL_TRACE_BLOCK, *PRTL_TRACE_BLOCK;

Windows Vista Kernel Structures