typedef struct _HARDWARE_PTE
{
     union
     {
          ULONG Valid: 1;
          ULONG Write: 1;
          ULONG Owner: 1;
          ULONG WriteThrough: 1;
          ULONG CacheDisable: 1;
          ULONG Accessed: 1;
          ULONG Dirty: 1;
          ULONG LargePage: 1;
          ULONG Global: 1;
          ULONG CopyOnWrite: 1;
          ULONG Prototype: 1;
          ULONG reserved0: 1;
          ULONG PageFrameNumber: 26;
          ULONG reserved1: 26;
          ULONG LowPart;
     };
     ULONG HighPart;
} HARDWARE_PTE, *PHARDWARE_PTE;

Windows Vista Kernel Structures