Rox 9.0 Advice

[Legpower]

Why are there 3 home altitudes on the Rox 9.0

When setting up for altitude/Incline one has three values to enter in:

 

1) The home altitude i.e. where one lives or stays

 

2) The altitude of where one is riding.  I assume at the start of the ride.  Does one set this everytime one is starting a ride.

3) Or one can set the Barometric pressure reduced to sea level in lieu of 2 above.   If one does take option 2 does one set option 3 to 0 or vice versa

 

Where can one get a detailed information of the information required above....and no weather sites only provide information where there is a weather station.