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