It definitely works. You need to choose Type custom. I don't believe the custom types are very useful though -- as well there's not a single example or documentation on how to use them. From what I've been able to do with them, they seem extremely limited in functionality.

It would be much more useful to me if I could choose one of the existing Types and customize that. As opposed to having to choose Custom and lose all the features of the pre-existing Outline types.

The Custom (begin1/end2) is easy enough to figure out, though it's so limited as to make me wonder why it even exists: You can have 1 and only one begin string, and one and only 1 end string --- unless you use a non-discriminating regex for both that would match anything, eg
Quote:
Except now an open brace { can be closed with "return".

Customization of the Outline format is probably one of the few features I find in need of a complete overhaul in EmEditor.