Definition of Product System and Solving Multifunctionality in ISO 14040–14044: Inconsistencies and Proposed Amendments—Toward a More Open and General LCA Framework - Schaubroeck, Thomas; Schrijvers, Dieuwertje; Schaubroeck, Simon; Moretti, Christian; Zamagni, Alessandra; Pelletier, Nathan; Huppes, Gjalt; Brandão, Miguel (Frontiers in Sustainability, 2022)