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