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