In the rich text editor:
@P4inx2
In a comment:
[P4inx2](https://chowlings.com/user/P4inx2)
For Names and Avatars:
In the rich text editor:
%P4inx2
In a comment:
[![P4inx2's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/P4inx2) [P4inx2](https://chowlings.com/user/P4inx2)