Which ECC application tables are used as a source for the Celonis P2P activity table

We need to validate whether the activity table captures all the necessary events and data flows for the PO line items and for that we need to know the ECC application tables used to build the activity table for P2P.
I tried checking the CDHDR and CDPOS but I didn’t find the one-to-one link between these tables and activity tables. Which all tables are used for building the activity tables for P2P?