In the rich text editor:
@sugarconcrete
In a comment:
[sugarconcrete](https://chowlings.com/user/sugarconcrete)
For Names and Avatars:
In the rich text editor:
%sugarconcrete
In a comment:
[](https://chowlings.com/user/sugarconcrete) [sugarconcrete](https://chowlings.com/user/sugarconcrete)