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