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