If you use the py3o reporting engine (module *report_py3o* from the `reporting-engine <https://github.com/OCA/reporting-engine>`_ OCA project) to generate your PDF invoices and you want these PDF invoices to be Factur-X invoices (i.e. a PDF invoice with an embedded XML file in CII format), this module is for you ! Factur-X is the e-invoicing standard for France and Germany (in Germany, it is also called ZUGFeRD 2.1).
