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