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