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