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