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