There are many prices in DP but the one that is most used is the "Invoiced price". It's calculated by DFU and it's based on file BW_IH (Invoiced History), which takes the invoiced documents starting from January 1st of Year-3 (if we are in April 2021, we take the documents starting from January 2018).
The spec of BW_IH can be found here.
> For the past: using the Invoiced volumes + Invoiced Gross/Net Sales, we can calculate the historical Invoiced price month by month in the past = Invoiced Gross/Net Sales / Invoiced quantity.
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