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