Hi, I am the one responsible for CPview.
The behavior changes between data - it might be the maximum of that minute, average during the minute, a sample done exactly at that time, or even other behaviors (like the one described below).
Unfortunately, we don't yet have a good document to specify this behavior for each metric - but we are working on it. Once we have everything (or at least the most important metrics) mapped, we will release this documentation and I will post about it in Check Mates, so keep an eye out for it.
If you want to find out the behavior for a specific metric, please approach me directly and I will do my best to answer.