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