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