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