If an incoming item value contains deltas, a preprocessing script that simply adds the incoming value up to the last value would be useful in order to obtain an overall counter that stores the sum of all received deltas.

The implementation could be very similar to the "Simple Change" preprocessing filter, just with an addition operator instead of computing the difference of the current and the last value.

I have added a similar feature request ZBXNEXT-9454 as an alternative, that would provide the same functionality by using JavaScript.