Schematron is an ISO standard (ISO/IEC 19757-3) for making assertions about XML documents using XPath expressions. Unlike XSD (which validates structure), Schematron validates business rules — e.g. "if VAT rate is 0%, a reason must be provided".
In e-invoicing, Schematron rules are the primary mechanism for enforcing EN 16931 compliance. PEPPOL, ZUGFeRD, and national e-invoice formats all ship Schematron rule sets that must pass before an invoice is accepted.
Key facts
- ISO standard: ISO/IEC 19757-3
- Uses XPath assertions inside
<assert>and<report>elements - Applied after XSD validation as a second validation pass
- Official EN 16931 Schematron rules maintained by CEN/TC 434