In the rich text editor:
@calciumMUTT
In a comment:
[calciumMUTT](https://cometcrashers.org/user/calciumMUTT)
For Names and Avatars:
In the rich text editor:
%calciumMUTT
In a comment:
[](https://cometcrashers.org/user/calciumMUTT) [calciumMUTT](https://cometcrashers.org/user/calciumMUTT)