This means that re-arranging the pages in the outline does not require you to fix all these links on the pages. They are automatically adjusted. The Outline Library creates a tuple structure representing the structure of the Web Site. There is one tuple per page or section. As parameter they get the tuple representing the page internally.
Tags take a tuple representing a section or page as argument.
Some Outline Tags have an additional parameter o defaulting to the main menu. By giving them another page as parameter, the menu or Table of Contents can be created with another starting section. Other Outline Tags have an additional parameter o defaulting to the current page or section.