Earlier, you saw how address translations are resolved when the PTE is valid. When the PTE valid bit is clear, this indicates that the desired page is for some reason not (currently) accessible to the process. This section describes the types of invalid PTEs and how references to them are resolved.
Only the 32-bit x86 PTE formats are detailed in this book. PTEs for 64-bit systems contain similar information, but their detailed layout is not presented.