PageVersioning is a mechanism for creating better DocumentMode pages.
When we get active participation on a topic we can degenerate quickly into ThreadMess. PageVersioning takes a snapshot of the page, renames it elsewhere for reference, and then massively refactors the page that needs rework.
At times this can result in a fork, with both the new page (and the old) able to stand on their own. See WikiMaster and WikiMasterOriginal for an example of this.
There are also times where the mess is mostly created in the page by one person. And then a reminder comes to "clean it up", so a page version is created and in that instance, it is intended that the versioned page eventually goes away. See WebServices and WebServicesOriginal for an example.