Danny: Could you elaborate on the usecase and provide an example, please?

An example is pages in a Help namespace that match up with a Template, Module, or other namespace.

There are a few possibilities, such as using specific always-bound namespaces (like adding "Template help:" that's bound along with "Template:" and "Template talk:") or creating meta namespaces like 'Help:Template:Foo' matching up with 'Template:Foo'. This latter method is used (without the move binding magic) on some of the Czech wikis -- for instance Nápověda:Šablona:Autorinfo is help page for Šablona:Autorinfo, and should move along with it if it's renamed ideally.

There's also the strategy we're thinking about for templates under multi-content revisions, where the help/description "page" might be turned into one of the content slots directly on the Template: page. That would avoid having to track down the page, but will be a longer trek before we do those.

A bunch of useful things that could fall under "binding" pages:

• Groups of pages should be able to be added to a watchlist at once. When new pages are added to the group, the new pages should automatically be added to the watchlist.
• Joint history pages, showing all changes to all pages in the group.
  • Currently, in some situations, editors have just added a separate page with links to each contained page, and then used Special:RelatedChanges to track things. Very inconvenient.
• Grouped edits. Users should be able to edit multiple pages within the group at once, which would be saved simultaneously, and would ideally appear as one edit in the group history page.
  • User should also be able to preview pages including changes to transcluded pages in the group while editing the group. That is, if a group contains Page1 and Page2, and Page1 transcludes Page2, editing Page2 and previewing Page1 should include Page2's changes.
• Renaming, protecting, and deleting groups of pages is quite a hassle at the moment. These should be possible to do as a group.

This has quite a lot of usecases:

• Templates have subtemplates, documentation, test pages, i18n, and modules, many of which should be edited together.
  • Currently, tests are handled by using either the template sandbox or by using "Preview page with this template" (which is unavailable in the new wikitext editor), both of which are not so easy to use. An easier way would be to allow just editing the template and then pressing "Preview" below the test page content, on the same edit screen.
• Books on Wikibooks and Wikisource should have grouped watching/history/moving/etc.
• Gadgets have scripts, CSS, various bits of localization and documentation, sometimes specialized templates. These should have grouped watching/editing/history. Changes to individual components are sometimes dependent on each other.

Lots of pages have an arbitrary amount of associated pages with any amount of content models, usually with each of them needing their own pages. Many of these issues could not be solved with MCR.