In the rich text editor:
@SunSun001
In a comment:
[SunSun001](https://chowlings.com/user/SunSun001)
For Names and Avatars:
In the rich text editor:
%SunSun001
In a comment:
[![SunSun001's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/SunSun001) [SunSun001](https://chowlings.com/user/SunSun001)