typedef struct _MM_PAGE_ACCESS_INFO_HEADER
{
     SINGLE_LIST_ENTRY Link;
     MM_PAGE_ACCESS_TYPE Type;
     union
     {
          ULONG EmptySequenceNumber;
          ULONG CurrentFileIndex;
     };
     UINT64 CreateTime;
     union
     {
          UINT64 EmptyTime;
          PMM_PAGE_ACCESS_INFO TempEntry;
     };
     union
     {
          struct
          {
               PMM_PAGE_ACCESS_INFO PageEntry;
               ULONG * FileEntry;
               ULONG * FirstFileEntry;
               PEPROCESS Process;
               ULONG SessionId;
          };
          struct
          {
               ULONG * PageFrameEntry;
               ULONG * LastPageFrameEntry;
          };
     };
} MM_PAGE_ACCESS_INFO_HEADER, *PMM_PAGE_ACCESS_INFO_HEADER;

Windows Vista Kernel Structures