In the rich text editor:
@a-shark
In a comment:
[a-shark](https://chowlings.com/user/a-shark)
For Names and Avatars:
In the rich text editor:
%a-shark
In a comment:
[![a-shark's Avatar](https://chowlings.com/images/avatars/2496.jpeg?v=1728003113)](https://chowlings.com/user/a-shark) [a-shark](https://chowlings.com/user/a-shark)