In the rich text editor:
@TH30
In a comment:
[TH30](https://chowlings.com/user/TH30)
For Names and Avatars:
In the rich text editor:
%TH30
In a comment:
[![TH30's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/TH30) [TH30](https://chowlings.com/user/TH30)