Admin:
You might want to look at these forums:
(1) Eng-Tips Forums at
www.eng-tips.com/threadminder.cfm?pid=798, scroll to bottom of page and click on "Process TGML" and see their extensive list of tags.
(2) Chemical-Engineering-Forum at
chemical-engineering-forum.com/index.php?action=post;board=1.0 and see their [sup] and [sub] tags.
(3) CR4 Forum at
cr4.globalspec.com/edit/newthread?f=9 and see their
X2 and X
² tags.