XML Syntaxes
UBL vs. UN/CEFACT CII
XRechnung supports two XML syntaxes: OASIS UBL 2.1 and UN/CEFACT CII D16B. Both comply with EN 16931 — but they differ significantly in structure, adoption and tooling.
| Criterion | OASIS UBL 2.1 | UN/CEFACT CII D16B |
|---|---|---|
| Standards body | OASIS (Organization for the Advancement of Structured Information Standards) | UN/CEFACT (United Nations Centre for Trade Facilitation and Electronic Business) |
| Full name | Universal Business Language 2.1 — Invoice | Cross Industry Invoice D16B |
| Adoption in Germany (XRechnung) | Very common — preferred syntax for many software vendors | Also common — basis of ZUGFeRD/Factur-X |
| Adoption in Europe | Scandinavia (PEPPOL BIS), UK, Belgium prefer UBL | France (Factur-X), Germany (ZUGFeRD) prefer CII |
| XML namespace prefix | cbc:, cac: (CommonBasicComponents / CommonAggregateComponents) | ram:, rsm:, udt: (UN/CEFACT-specific) |
| XML readability | Relatively readable, English element names | More compact, but cryptic; many abbreviations |
| Use in PEPPOL network | PEPPOL BIS Billing 3.0 is based on UBL | Not native in PEPPOL standard; mapping required |
| Use in ZUGFeRD/Factur-X | Not used — ZUGFeRD uses CII exclusively | Basis of the embedded XML in ZUGFeRD and Factur-X |
| Validators | KoSIT Validator (UBL Schematron), PEPPOL Validator | KoSIT Validator (CII Schematron), Mustang Project |
| EN 16931 conformance | Yes — EN 16931-3-2 defines the UBL syntax binding | Yes — EN 16931-3-3 defines the CII syntax binding |
Verdict
UBL and CII deliver semantically identical invoice data — the choice of syntax mainly depends on the ecosystem. Those using PEPPOL networks or targeting international partners in Northern Europe are better served by UBL. Those creating ZUGFeRD hybrid invoices or working with French partners need CII. For XRechnung to German authorities, both syntaxes are equally accepted.
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