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