The PDF/A-3 container — following the ZUGFeRD model #

A structured record is of little use if no human can read it any more — and a pretty PDF is of no use to a machine. Prexfo solves this like the successful electronic invoice ZUGFeRD: both live in one file.

The principle #

A PDF/A-3 document shows the content to the human in the usual form. Embedded in the same document is the machine-readable prexfo.xml as an attachment. Whoever only wants to read opens the PDF. Whoever wants to process the data extracts the XML. Both see the same truth.

Why PDF/A-3 of all things? #

Only PDF/A-3 allows the embedding of arbitrary file attachments — the precondition for carrying the prexfo.xml. At the same time, the PDF/A part guarantees long-term archivability: the document stays readable for decades without special software.

The technical rules #

• The prexfo.xml is embedded as an Associated File.
• The relationship (AFRelationship) carries the value Alternative — the XML is the machine-readable alternative to the visible content.
• The embedded file name is standardized: prexfo.xml.
• XMP metadata uniquely identify the document as a Prexfo document and state the version and schema namespace — so software recognizes a Prexfo document without parsing the whole content.

Proven, not invented. ZUGFeRD has shown that millions of invoices can be human- and machine-readable. Prexfo carries this model from the document “invoice” over to every document in the life of a property.