What does ascent and descent stand for?

Problem: In the altitude histogram, TrailRunner mini displays two values derived from altitude values. These are named ascent and descent. What's the meaning of these?
Description: Ascent is the gain of only positive altitude differences. Descent is the opposite.
Example: With an altitude series of 10, 13, 15, 13, 11, 16 the 
absolute elevation difference from the highest summit down to the lowest point would be 10..16 = 6
the ascent is 10..15 + 11..16 = 10
and the descent is 15..11 = 4