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