Add Invert
Main Menu or GNSS Toolbar | Measure Modes | Add Invert
If you've manually measured a distance to an invert, you can have FieldGenius compute a point with a computed invert elevation.
When you start the command you will see the Invert Toolbar appear towards the bottom of your main screen.

First you need to specify the point that will be referenced to compute the invert elevation. You can do this by using the point chooser button.
Now enter the measured distance to the inverse. For example if your measurement was 5.5', FieldGenius will subtract this from the reference point's elevation. Entering a negative value will cause it to be added.
Press Store Point to create and save a point with the calculated invert distance. This point will have the same northing and easting value as the reference point.
Note:
While the invert toolbar is open, you can continue entering invert measurements or choose different reference points.
Raw File
When you save the point, an offset and store point record will be created.
--OS,OP7,FP8,ND0.000,ED0.000,LD5.000
SP,PN8,N 935.976,E 1232.356,EL5.000,--<No Desc>