CEN: eInvoicing Semantic Data Model EN 16931-1:2017 Electronic invoicing - Part 1: Semantic data model of the core elements of an electronic invoice https://standards.cen.eu/dyn/www/f?p=204:110:0::::FSP_PROJECT,FSP_LANG_ID:60602,25&cs=1EDAF8ACA5277C7EF32DC6EFAEF077D41