Portable Document Format’ is a file format used to present documents in a manner independent of application software, hardware, and operating systems. Each PDF file encapsulates a complete description of a fixed-layout flat document, including the text, fonts, graphics, and other information needed to display it. In e-invoicing it is the principal method by which a human readable presentation of the invoice or another document is delivered. A PDF may be machine or humanly generated. PDF/A3 as a recent version is growing in use.