NPM and Netflow - How are the values calculated and how should we interpret the timestamp

Hello,

We set the polling frequency of the NPM module to 5 minutes (to get for instance the In/OutAveragebps of interfaces).

When we query the DB, we have for instance:

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1. Are the values of In/OutAveragebps the number of bits transferred during the period of 5 minutes divided by 300s or are these values calculated differently?
2. Does the timestamp indicates the beginning or the end of the period? In other words, the value of the second line gives the traffic between 9:03:28 and 9:08:28 or between 9:08:28 and 9:13:28?

Same questions for the Netflow. In that case it is no longer polling as I understood but the Netflow generates a report every minute:

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3. Are the values of In/egressBytes the number of bytes transferred during 1 minute or are these values calculated differently?

4. Does the timestamp indicates the beginning or the end of the period? In other words, the value of the first line gives the traffic between 7:58:00 and 7:59:00 or between 7:59:00 and 8:00:00?

Thanks for your help, Kind regards

Livio