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