Date: 2025-10-01
Accepted
There are different kinds of PDF files. We need to decide which one we want to comply with.
There are different PDF/A conformance levels and versions. The Bundesarchive recommends using PDF/A-2a, PDF/A-2u, PDF/A-2b, PDF/A-1a, ... in that order.1 Weasyprint does not support creating PDF/A-2a files. It can create PDF/A-2u conforming files.
The newest PDF-Version supported by PDF/A-2u and PDF/A-2a is PDF 1.7. PDF 2.0 is not compatible with PDF/A-2u or PDF/A-2a.
If a PDF/A-2u-file is properly tagged for accessibility it should also confirm to most of PDF/A-2a. But the metadata indicating this is not set by weasyprint. We can adjust the metadata in a post-processing step.
For accessibility there are also the PDF variants PDF/UA-1 and PDF/UA-2. PDF/UA-2 requires PDF 2.0.
We create PDF/A-2a files in PDF-Version 1.7. We use weasyprint to create PDF/A-2u files and then adjust the metadata to indicate that it is a PDF/A-2a compliant. We ensure this compliance by setting up weasyprint to created tagged-PDFs.
We do not indicate PDF/UA-1 compliance, even though the created files comply to it (with the exception to the rule checking that the metadata indicate PDF/UA-1 compliance). Setting these metadata in a PDF/A-2a compliant way is not that simple and would require a lot more work.
We create PDF-files in a version that is both accessible and also long-term-archivable.