typedef struct _HBASE_BLOCK
{
     ULONG Signature;
     ULONG Sequence1;
     ULONG Sequence2;
     LARGE_INTEGER TimeStamp;
     ULONG Major;
     ULONG Minor;
     ULONG Type;
     ULONG Format;
     ULONG RootCell;
     ULONG Length;
     ULONG Cluster;
     UCHAR FileName[64];
     GUID RmId;
     GUID LogId;
     ULONG Flags;
     GUID TmId;
     ULONG GuidSignature;
     ULONG Reserved1[85];
     ULONG CheckSum;
     ULONG Reserved2[882];
     GUID ThawTmId;
     GUID ThawRmId;
     GUID ThawLogId;
     ULONG BootType;
     ULONG BootRecover;
} HBASE_BLOCK, *PHBASE_BLOCK;

Windows Vista Kernel Structures