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