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