Thread:Edkaufman/@comment-28061314-20170619213146/@comment-4651179-20170619214640

If it doesn't bother you, I'll be taking this question because Edkaufman hasn't been around for a year.

By Marvel's standards, a universe is essentially a timeline. This means it's taken for granted that an alternate universe is in a different timeline, because they are a different timeline per se.

The numeric designation of all realities that are written as "Earth-#" is official. They are either given in the comic they debut, in handbooks, or in this officially-endorsed handbook appedix.

The realities that don't have an official designation are given a Temporary Reality Number (TRN for short). It's explicit in the TRNs page that they are not an official designation, and that their creation stems solely from the need to add their information in the site. Additionally, the article of every reality with a TRN makes it clear the designation used is un-official.