In the rich text editor:
@Catalyst
In a comment:
[Catalyst](https://chowlings.com/user/Catalyst)
For Names and Avatars:
In the rich text editor:
%Catalyst
In a comment:
[![Catalyst's Avatar](https://chowlings.com/images/avatars/1196.jpeg?v=1649853276)](https://chowlings.com/user/Catalyst) [Catalyst](https://chowlings.com/user/Catalyst)