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