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