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