Syntaxes and formats

The pillar guide

Syntaxes and formats explained: UBL, CII and national formats - How the same semantic model is encoded in different syntaxes, and how to choose without confusing syntax with meaning.

Working guides in this topic

• Choosing a syntax with a trading partner - A short agreement: profile, syntax, version, validation rules and test invoice, before live exchange.
• Cross Industry Invoice (CII) syntax: structure and use - The UN/CEFACT CII message, its header and line structure, and where it is the expected syntax.
• Factur-X and ZUGFeRD hybrid formats - A PDF with embedded structured data, the profiles that govern it, and the rule for which layer is authoritative.
• Format testing with sample invoices - Sample invoices that test lines, allowances, tax, references and edge cases, not only the happy path.
• Format version migration without breaking live exchange - Running two versions in parallel, testing the new version, and retiring the old version with a date both sides agree.
• JSON and API invoice formats - When an API payload is an invoice record, when it is only a transport form, and how to keep the two apart.
• National formats and when they apply - Why some countries keep a national format, and how to handle a national format beside a European profile.
• Syntax conversion between UBL and CII - Converting between bindings without losing business meaning, and the fields that need a human decision.
• UBL invoice syntax: structure and common elements - The UBL invoice document, its parties, lines and totals, and the elements most often mapped wrongly.
• XML validation and schema checks - Schema validation as the first gate, what it catches, and what it cannot catch about business meaning.

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