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