Collecting data on all the processes along the life cycle of a product is resource intensive. In general, a database provider can expect that users will resort to multiple databases and other data sources for their work. While some applications, such as PEF, require the use of specific data, it is generally more common to see practitioners use a variety of data sources. In this regard, it is strongly recommended that national databases be prepared to be interoperable with others. Data interoperability will allow for the simultaneous use of multiple data sources, improving robustness of results for the product systems or supply chains under study. Using a methodological handbook and/or a core set of background data that is used by the most widely available databases contributes to the interoperability. Existing handbooks and data that could be used are available from existing data providers, like ecoinvent and Sphera, or initiatives like the PEF or CDLCI.