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