Release notes

Release date: 13 November 2025

• Support for tagged content inside of PDF FormXObjects.
• Various improvements to AI checks.

Release date: 4 November 2025

• Improved performance of AI-supported checks when the system environment allows the use of the GPU (graphics card).
• Improved AI checks for incorrect assignment of H and P elements.

• On some systems (especially Parallels on Mac), the AI-powered checks did not work in Beta 1. This issue has been fixed.

Release date: 22 October 2025

PAC 2026 includes artificial intelligence (AI) functions. With these new features, PAC can now cover part of those Matterhorn Protocol checkpoints that previously required human judgment. This significantly reduces the amount of manual checking and makes professional PDF/UA testing much more accessible—especially for beginners.
You can find further information on this page.

Release date: 16 October 2025

• Bug fix where malformed links could unnecessarily cause checks to terminate.
• Fixed regression that caused performance issues.

Release date: 7 October 2025

• New warning when the Contents entry of an annotation is composed entirely of white space.
• The Tagged text consists of only whitespace quality check now also checks L, Table, Caption, and BlockQuote structure elements.
• The contrast check now no longer checks white space characters for contrast.
• Performance improvements when opening documents.
• PAC requires significantly less memory when processing documents.

• Bug fix regarding certain strings not being decrypted properly.
• Bug fix regarding the 'Widths' entry of a font descriptor not being properly taken into account when the font is one of the 14 standard fonts.
• Bug fix regarding color spaces consisting of a single name object in an array.
• Scroll bar has been removed from the header of PAC.
• Problems with the screen reader preview rendering certain form fields have been fixed.
• Fixed bug that caused some failures/warnings to not display their locations.
• Corrected logic in the structural parent tree check to no longer fail when a document has a tag tree without content items and a parent tree does not exist.
• Corrected logic in note has referring link on page check to also take the 'Dest' entry into account.
• The alignment of the numbers within the WCAG and Quality tabs has been corrected.
• Fixed bug that caused artifact entries to be duplicated when viewing them.
• Various rendering issues resolved.

Release date: 12 May 2025

• If no errors are found, the user interface displays “-” instead of “0” to make it easier to recognize.
• Improved color contrast check.

• A rendering issue has been fixed.
• Various bug fixes.

Release date: 11 March 2025

• Corrected a bug in the context of FormX objects

Release date: 6 March 2025

• The PDF rendering component has been updated to better handle an error with certain PDF documents.
• Date values outside of the supported .NET range are now supported (like time zones over +/- 14 hours)
• Content stream operators in illegal positions are treated as failures in the PDF syntax (instead of a PAC error).
• Invalid dates are treated as failures in the PDF syntax (instead of a PAC error).

Release date: 20 November 2024

• PDFs with malformed dates were previously causing errors in the checker, now they are listed as errors in PDF Syntax.
• The maximum size of the main window has been increased, due to user reports that it  was too restricting.

Release date: 8 October 2024

• New quality check: "P" elements contain "Note" elements.
• Translation improvements.

• The check "Marked content is present in admissible locations" has been moved to a different location (from the PDF/UA 32000 check set to the PDF/UA tagging check set).
• Various bugfixes.

Release date: 20 August 2024

• PDF 2.0 is now supported to a limited extent.
  PAC currently fully supports documents up to and including PDF standard 1.7.
  Documents based on newer standards are processed according to a "best try" approach. It is possible that errors or unreliable results may occur.
• The screen reader preview now properly shows all types of annotations and their values
• The contrast of text and soft hyphens in the screen reader preview has been improved
• Translations have been tweaked

Different small bugfixes

Release date: 18 April 2024.

• Comprehensive improvements to the internal functioning of the checks
• New Dutch translation and improved translations into other languages
• You can now select the language in which PAC is displayed
• PAC appears as small as possible on small screens
• The text fields for titles and filenames have tooltips
• You can copy the entire title/filename, even if it has been shortened
• You can double-click on individual checks on the main form (summary) to open the report form with the section already selected and expanded
• You can use the ESCAPE button to close the screen reader preview window

• Many bug fixes as part of the internal improvements mentioned above

Release date: 1 February 2024.

• PAC can be vertically resized.
• Stabilization of PAC enables faulty documents to be partially checked, any checks that fail are marked.
• In the screen reader preview, soft hyphens are highlighted to differentiate them from normal hyphens.
• User displays consistently across all screen resolutions.

• The document language in the metadata is checked more precisely in accordance with the PDF/UA and WCAG specifications.
• The report form displays pages with rotation more reliably.
• Several smaller bugfixes.

Release date: 5 December 2023.

The check Document language metadata is not ISO-compliant (WCAG) or Correctness of language attribute (Quality) was incorrect (too strict). In this hotfix, language attributes such as "en" (instead of "en-US") are also accepted.