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