XML metadata, jpg/thumb, and other behaviour Documentation

Does WD have a page or other documentation to describe what it expects to find in the XML file; that is - where is there documentation for the metadata files?

Also, I noticed that sometimes it creates a file.thumb for the image, but sometimes a file.jpg (both in jpg format) What are the rules about this? Does it matter? Which works better?

I’d also like to know what are the rules about treating a folder as a movie (like DVD/BD rips) as most of them are OK, but some of them are treated as folders. I’d really like to fix the issue(s) in my DVD/BD folders and get them all to work consistently.

And, when my HDDs are plugged into a USB hub the thumbs don’t show in gallery view on DVD/BD folders, but the folder.jpg shows up fine for other folders. Is this a bug, or a documented limitation of the device?

Also, is it possible to series metadata at the folder level, and what is different about this XML file vs the movie xml vs the episode xml file.

Lastly, what are the rules about treating content as if it were from a series vs a movie, and is there a way to override this behaviour?

If it matters, I’m running firmware version 3.00.28 (11/17/11) in my live hub.

Lots of questions, but this should be asked in the Themes forum.