In the rich text editor:
@IKA9
In a comment:
[IKA9](https://chowlings.com/user/IKA9)
For Names and Avatars:
In the rich text editor:
%IKA9
In a comment:
[![IKA9's Avatar](https://chowlings.com/images/avatars/default.jpg)](https://chowlings.com/user/IKA9) [IKA9](https://chowlings.com/user/IKA9)