Rules question re:elevations

[Xerxes77]

From the user manual:

"When the target unit is higher in Elevation than the firing unit and the firing weapon is not Indirect Fire, it gets an Elevation protection value. This protection value is equal to the difference in elevation in contour levels between the firing and target unit times the Elevation Protection parameter data value."

From the main prog manual:

"Elevation Protection: the increase in protection per 10 meters given to units that are fired upon from lower elevations."

The different scales used in these two passages is confusing me and I wonder if I'm missing something really simple.

If I'm playing on a map with an elevation delta of 50m per contour level and an Elevation Protection value of 2 as set in the Parameter Data, and I'm sitting on a hex at 500m with an enemy just below me at 450m, do I get just +2 additional protection (because there ¡s just one contour level between the firing unit and me), or should I use the "per 10 meters" rule and get 50/10 *2= +10?

Thanks in advance for your help.