An XSD (XML Schema Definition) is a W3C standard that describes the structure, elements, and data types an XML document must contain. In e-invoicing it is the first of two validation passes — XSD confirms the file is structurally sound before Schematron checks the business rules.
XSD catches basic errors like:
- 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