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