When you make changes on a master page, FrameMaker automatically updates all body pages using that master page. When you make layout changes on a body page (for example, by changing the number of columns, the gap between columns, or the margins), you create an override to its master page’s layout. You can then do any of the following:
Update the master page and all corresponding body pages with your changes.
Create a master page based on the body page changes.
Do neither of the above, leaving the override as a one-time-only page layout.