WP2 aims at identifying and addressing relevant data gaps and inconsistencies. Traditionally, MFAs are used to map material cycles and visualize them in Sankey diagrams. This is done by defining systems and quantifying them using a wide variety of data sources. One of the greatest challenges for conducting MFAs is the fact that the data used tend to be incomplete, highly fragmented, and non-transparent (meaning of the statistics used is unclear). MFA specialists usually address this challenge by using highly aggregated systems, crude approximations, and mass balances. This approach is useful for providing crude overviews, but that tends to hide potentially relevant details as well as inconsistencies; it results in “crude maps with hidden gaps”. WP2 employs MFA in a different and new way, aiming at developing “refined maps with explicit gaps”. The goal of WP2 is to involve the major global data providers in a common process for developing an MFA approach for mapping the exact locations (within a system) of the data reported. These refined maps are used to highlight relevant data gaps and inconsistencies within and between sectors and countries. WP2 further develops a generic data structure that allows data providers to report their data together with their exact “coordinates” (system context), which greatly facilitates data exchange between different institutions and common efforts for addressing data gaps and harmonizing data reporting.