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