XRechnung
XRechnung is the German national e-invoice standard, a purely structured XML format defined as a CIUS of the EN 16931 European norm.
XRechnung is XML only, with no visual layer. It became mandatory for invoicing German public bodies and is a common choice in business-to-business exchange too. The data model follows EN 16931, using either the UBL or the CII syntax underneath.
Because it is pure data, an XRechnung can flow straight into bookkeeping without OCR. The catch is that a human cannot read raw XML, so a good tool renders it as a readable invoice.
Cortena reads XRechnung files, shows them as a normal invoice, and codes them line by line.