An XSD (XML Schema Definition) is a W3C standard for describing the structure, content, and data types of an XML document. In e-invoicing, XSD validation is the first of two validation passes — it verifies that the XML is well-formed and structurally correct before Schematron checks are applied for business rule compliance.
XSD validation catches errors such as:
- Missing mandatory elements
- Elements in the wrong order or namespace
- Wrong data types (e.g. a date field containing free text)
- Invalid cardinality (e.g. two
<ID>elements where only one is allowed)
Key facts
- Standard: W3C XML Schema 1.0 / 1.1
- File extension:
.xsd - Used in: UBL 2.1 (OASIS publishes official XSDs), UN/CEFACT CII, XRechnung
- Validation order: XSD first → Schematron second
- Tools: Saxon, Xerces, libxml2,
xmllint --schema