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