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