For shows like Firefly where the episodes aired in a different order than the creators intended.
Not sure yet about the implementation details, but it would probably be something like: if there are alternate episode lists created for a show, a dropdown would appear on the show's episode list that allows you to switch between the different schemes.
Alternate lists for DVD ordering are now live!
For an example, see Firefly where you can click through to the DVD release list: https://www.tvmaze.com/alternatelists/1/firefly-dvd-release. To create a new Alternate List for a show, go to the show's edit page (e.g. https://www.tvmaze.com/show/update?id=36745) then click on Alternate Lists in the menu.
For all the details, read the new policy on Alternate Lists at https://www.tvmaze.com/faq/40/alternate-episodes
