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