custom Notification variable

Hi Gurus,

I have created custom Template ID, Message class and Doc Object.

My Question is, can we able to create custom Notification variable? Because i am seeing all the standard variable are related to the Access request fields.

But my custom notification variable should be from the selected Role fields in the Access Request.

In this scenario, i have created a custom field in the Business Role. whenever a business role selected and approved by the role owner, then that custom field details should come in the notification message to the next approver.

Hope i am clear in my question.

Thanks,

Sriram.