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