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