How to select DTMs
Click Calculate on the home screen.
Click Surface.
Click Volumes.

Select the Design Surface drop-down menu, and click the List icon.
Select the design surface from the list.
Confirm the information with the green check mark icon, and click the Return (orange arrow) icon.

Select the Original Surface drop-down menu, and click the List icon.
Select the original surface from the list.
Confirm the information with the green check mark icon, and click the Return icon.

How to calculate volumes
Click Calc.
The volumes are shown.
