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