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