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