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