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