In the rich text editor:
@Gidget
In a comment:
[Gidget](https://chowlings.com/user/Gidget)
For Names and Avatars:
In the rich text editor:
%Gidget
In a comment:
[](https://chowlings.com/user/Gidget) [Gidget](https://chowlings.com/user/Gidget)