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