Question: Why do you need PDF/A?

Answer: The PDF/A standard for long-term archiving was adopted by ISO (International Standards Organization) in autumn 2005. The PDF/A standard aims to enable the creation of PDF documents, the visual appearance of which will remain the same over centuries. It is conceived for users who want to be sure that their documents contracts, invoices or technical documentation are legible and useable even after 10, 50 or 100 years.

That the inventor of the PDF format, Adobe Systems, has revealed its format implies for users and developers, an assurance that programs will be available for generation and display of PDFs even after decades. However, only the PDF/A standard can guarantee that users will be able to view exactly the same content as when their documents were created.

Question: How does PDF/A differ from normal PDF?

Answer: Based on PDF Version 1.4 (corresponding to Acrobat 5), the PDF/A standard includes a number of minimum requirements and restrictions, ensuring that PDF documents are always reproduced in a unique manner.

Question: PDF/A has two different peculiarities. What is the difference?

Answer: The PDF/A standard recognizes PDF/A-1a and PDF/A-1b. PDF/A-1b (basic) addresses the integrity of the visual display. PDF/A-1a (accessible) also requires the content of a PDF document to be marked up so that its logical structure (tagged PDF) is still recognizable. It also requires sufficient character set information so that the entire text can be interpreted as Unicode, which is an important requirement to be able to search through or extract text in PDF and for barrier-free use.

Question: What are the key rules for PDF/A?

Answer: The most important requirements, limitations and rules for PDF/A files:

• Dynamic objects are not permitted
• No external references or dependencies
• No embedded files (e.g. Word files)
• No embedded audio or video files
• Fonts must always be embedded and must contain all the letters (glyphs) used
• Colors must be clearly specified
• Forms, comments, notes are only permitted to a limited extent, and must behave in the same way on screen display and on printout
• Compression: LZW or JPEG2000 must not be used
• No transparent objects
• Functions that are not defined in PDF 1.4 must not be used (e. g. levels, 3D models)
• No proprietary PDF extensions
• Metadata must be coherent in itself
• PDF/A record must be included in metadata