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