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