In the rich text editor:
@Beryluma
In a comment:
[Beryluma](https://www.worldofgaia.org/user/Beryluma)
For Names and Avatars:
In the rich text editor:
%Beryluma
In a comment:
[](https://www.worldofgaia.org/user/Beryluma) [Beryluma](https://www.worldofgaia.org/user/Beryluma)