How do you interpret altitude data in Geo Tracker logs?

[John Rose]

I went for a ride up a hill nearby (mostly to partially drain the battery for balancing) and I logged it with the Geo Tracker app (by Ilya Bogdanovich) for Android. I started and stopped the record in my driveway.

I find the altitude data rather confusing though.

Altitude difference	120 m
Max altitude	103 m
Min altitude	-16 m (there was one stretch lower than my driveway)
Vertical ascent	160 m
Vertical distance	309 m
Vertical speed	0.15 m/s

I would've thought that "altitude difference" would be from "altitude min" to "altitude max", or 16+103=119
I have no idea where the numbers come from for the last three.

[later] Ah. I can make a screenshot and attach it.
The biggest climb is going along the straight "pot handle" section from the lower left corner of the lake up the turn-off to "Beech Hill Park".
The side-trip through "Ogden Mill" was on the way back.

[handlebar]

I calculate a vertical speed of .1469 m/s. 

I guess your minimum was between -16 and -16.5, and your maximum was between 103 and 103.5, and the sum was between 119.5 and 120.0.

Vertical distance would be all your up distances added to all your down distances.