UBL or CII: identify an invoice XML file

XML describes a way of organising data, not a single invoice format. Two files with the same extension can belong to different families. UBL and CII are syntaxes used to represent EN 16931 invoice information; a chosen profile then adds its own constraints.

Identify the document

Open the file in a text editor or use a tool that reports its detected type. UBL uses roots including Invoice and CreditNote, while CII uses CrossIndustryInvoice. The local name is insufficient: namespaces and profile identifiers also matter. Changing an XML prefix does not convert the content.

Choose the checks

Start with the actual syntax, then select the ruleset expected by the recipient. A UBL invoice is not automatically Peppol; a CII invoice is not automatically Factur-X. The validation report should identify the profile checked. A profile mismatch can produce many messages that disappear after fixing configuration, without arbitrarily changing amounts.

Convert with business checks

Before conversion, compare the information both profiles can express. Test references, taxes and attachments, then reconcile totals. Renaming the file or moving tags is not a reliable conversion. Keep a documented mapping between source fields and exported fields. Include a representative exception, such as a discount or missing optional reference, so that the mapping is tested beyond an ideal example.

Check your own case reproducibly

Work on a copy first and retain the unchanged original. Record the expected result, the action actually performed and the software version used. Afterwards, compare the document number, parties, currency and amounts with the original invoice. Investigate any difference before reusing the result. A small anonymised example is more useful for diagnosing a failure than indiscriminately sharing complete customer records. Repeat the test after changing an export setting and, where relevant, confirm that the actual business partner can receive and process the resulting document.

Sources and next steps

• ConnectingEurope : EN 16931.
• OASIS : UBL 2.1.