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