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PDF/A-3 vs. PDF/A-4: Understanding the Differences

Confused by PDF standards? We break down the key differences between PDF/A-3 and the new PDF/A-4, and which one you should use for archiving.

Comparison chart showing the evolution of PDF/A standards

PDF/A-3 vs. PDF/A-4: Understanding the Differences

The PDF/A standard (ISO 19005) is the global benchmark for the long-term preservation of electronic documents. It ensures that a file created today will be readable 50 or 100 years from now.

But PDF/A isn’t a single standard; it evolves. For years, PDF/A-3 was the cutting edge. Now, PDF/A-4 has arrived.

What is the difference? And does your organization need to upgrade?

1. A Quick History

  • PDF/A-1 (2005): The original. Very restrictive. No transparency, no layers.
  • PDF/A-2 (2011): Added support for JPEG 2000, transparency, and layers.
  • PDF/A-3 (2012): The game changer. Allowed embedding of arbitrary file formats.

2. The PDF/A-3 Revolution: “The Container”

PDF/A-3 is identical to PDF/A-2 in terms of rendering. The big difference is that it allows you to embed any file type inside the PDF.

This enabled the ZUGFeRD invoice standard in Europe. A ZUGFeRD invoice is a human-readable PDF/A-3 file that contains a machine-readable XML file embedded within it. A human reads the PDF; a computer reads the XML. Both travel together in one file.

3. Enter PDF/A-4 (2020)

PDF/A-4 is based on the modern PDF 2.0 specification (ISO 32000-2). It simplifies the standard and removes the “conformance levels” (A, B, U) that confused users in previous versions.

Key Changes in PDF/A-4:

  • Simplified Conformance: No more “Level A” (Accessible) vs “Level B” (Basic). PDF/A-4 files are just PDF/A-4. (Though there are two specific sub-profiles, see below).
  • Javascript Support: Limited support for JavaScript is now allowed for specific interactive purposes, which was strictly forbidden before.
  • Better Color Handling: Improved support for modern color spaces and spectral data.

The Sub-Profiles:

  • PDF/A-4f: Allows embedding of arbitrary files (replacing the functionality of PDF/A-3).
  • PDF/A-4e: Designed for engineering documents (replacing the old PDF/E standard), supporting 3D content and rich media.

4. Which Should You Use?

Stick with PDF/A-3 if:

  • Your existing workflows are stable.
  • You rely on specific tooling that hasn’t updated to PDF 2.0 yet.
  • You need the specific “Level A” (Accessibility) designation for compliance reasons that explicitly reference older standards.

Move to PDF/A-4 if:

  • You are building a new archive system from scratch.
  • You need to archive documents with modern features like 3D models or complex transparency that PDF 2.0 handles better.
  • You want to simplify your compliance requirements by dropping the A/B/U distinction.

Conclusion

Both PDF/A-3 and PDF/A-4 are excellent choices for archiving. PDF/A-3 is the mature, widely supported workhorse. PDF/A-4 is the modern, streamlined future.

Future-proof your archives. MergeCanvas supports generating compliant PDF/A files to ensure your records stand the test of time.