Email notification attributes

We are using SD 7.6.2 I'm trying to add a few attributes into our HTML email notifications for incident management. They are being generated as part of the incident management process. 

Specifically, when an incident is canceled I would like for the cancellation reason to be part of the notification email.

How do I find the attribute place holder to put in the HTML code to display the correct attribute in the notification e-mail?

Thanks,

Scuddy