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