show usergroup html markup in moderated forum

[CoffeeLovesYou]

Hi.
How can I make it show a person's usergroup HTML markup in the forum they're a moderator of only?
For example;
UserA is a moderator of ForumID 5.
If UserA posts in ForumID 5, I want their username to show with markup. However, if UserA posts in ForumID 15 (which they don't moderate), their username shows with no markup. Of course, I want their username to show with markup outside of the forums, too, like profiles, and who's online as they normally would, but I only want the usergroup mark up to show if they post in the forum they moderate.. otherwise, don't show it. How can I do this? I know a forum that does this but I don't want to ask them how they did it.

--------------- Added [DATE]1386800642[/DATE] at [TIME]1386800642[/TIME] ---------------

Bump. Is there a way to do this?
I know how to make it show to a user if they ARE a moderator (like, if I'm UserA and I'm a moderator of forum 5, then I can see it) but I don' know how to make it show for ALL users if UserA posted in forum 5 and is a moderator.

--------------- Added [DATE]1386811246[/DATE] at [TIME]1386811246[/TIME] ---------------

Bump. Is there a way to do this?
I know how to make it show to a user if they ARE a moderator (like, if I'm UserA and I'm a moderator of forum 5, then I can see it) but I don' know how to make it show for ALL users if UserA posted in forum 5 and is a moderator.