CCVC aren’t you thinking to simple?
I think the post-opener wanted a mileage calculator which automaticaly calculates the mileage between two endpoints (for example 2-cities).
- Find out distances between 2-endpoints (latitude+longitude) on a map for example
- do the calculation
- everything live on screen (screen-viewed calculator)
But all these you would found faster, if you would also take a look into the VELO-FORUM.