Once you have measured the eight surface points in "Step 3: Measure Features for Datum A", you can construct DATUM A from those points.
To construct DATUM A:
Execute the measurement routine up to this point to measure the eight surface points. To do this:
From the Edit Window
toolbar (View | Toolbars | Edit Window),
select Clear Marked
.
This is done so that the manual alignment point (PNT1) is not
included when you select Mark All.
Select Mark All
When the "Ok to mark manual alignment features?" message appears, click NO.
Select Execute
. The eight
surface points are measured.
From within the Edit Window, ensure that the LAST line in the measurement routine is highlighted.
Select the Insert
| Feature |Constructed | Plane menu item or the Constructed
Plane button
from the Constructed Features toolbar (View | Toolbars | Constructed Features). The Construct Plane dialog box appears.

Select the
Best Fit option.
From the feature list, highlight the eight surface points measured in "Step 3: Measure Features for Datum A". In this example, the points are PNT2 through PNT9.
Type DATUM A in the ID box.
Click Create, and then click Close to add the plane feature to the measurement routine.