==== Introduction ====

What are the unique invalid page table formats within OpenVMS?

==== Details ====

There are 5 unique invalid page table formats. The invalid page table entry can be for:

  * **A demand zero page** - This type of entry would be built for uninitialized data, which is at least one page in size.
  * **A global page** - This type of entry would be built when running an image that is INSTALLed with the /SHARE qualifier or when the program has been linked against a shareable image which is also INSTALLed /SHARE.
  * **A transition page** - This type of entry would be a page that is on the free or modified page list.
  * **A page in the page file** - This type of entry would be a page found in PAGEFILE.SYS.
  * **A page that can be located through the section table entry** - Type type of entry would be used to allow the reading of a set of code or data pages from the image file.  It can be either global or process private.