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