PDF Association logo.



About the contributor
PDF Association

Mission Statement: To promote Open Standards-based electronic document implementations using PDF technology through education, expertise and shared experience for stakeholders worldwide.
More contributions
Participating in the PDF Techniques Accessibility Summit

The PDF Techniques Accessibility Summit’s objective is to establish a broad-based understanding of how PDF files should be tagged for accessibilty. It’s an opportunity to focus on establishing a common set of examples of accessible PDF content, and identify best-practice when tagging difficult cases.

Modernizing PDF Techniques for Accessibility

The PDF Techniques Accessibility Summit will identify best-practices in tagging various cases in PDF documents. Questions to be addressed will likely include: the legal ways to tag a nested list, the correct way to caption multiple images, the appropriate way to organize content within headings.

Refried PDF

My hospital emailed me a medical records release form as a PDF. They told me to print it, fill it, sign it, scan it and return it to the medical records department, in that order. In 2018? To get the form via email (i.e., electronically), yet be asked to print it? Did the last 20 years just… not mean anything! So I thought I’d be clever. I’d fill it first, THEN print it. Or better yet, never print it, but sign it anyhow, and return it along with a note making the case for improving their workflow. The story continues…

Slides and video recordings of PDF Days Europe 2018

You missed the PDF Days Europe 2018? Never mind! Here you can find the slides and video recordings of all 32 stunning sessions!

Using PDF/UA in accessibility checklists

PDF/UA, like PDF itself, is internally complex, but used correctly, actually makes things easier.

The technical side of the PDF/A standard

After the first part of PDF/A was published, two more parts arrived. These are not replacements for part 1, however; rather, they offer additional options for archiving PDF documents. All existing PDF/A files remain fully valid.

PDF/A-1: The first archiving standard

PDF/A-1 is based on PDF version 1.4, which first appeared in 2001. All resources (images, graphics, typographic characters) must be embedded within the PDF/A document itself. A PDF/A file requires precise, platform-independent colour data using ICC profiles, and XMP for the document metadata. Transparent elements, some forms of compression (LZW, JPEG2000), PDF layers, and certain actions or JavaScript are forbidden. A PDF/A file must not be password-protected. PDF/A-1 expressly supports embedded digital signatures and the use of hyperlinks.

PDF/A-2: Based on PDF 1.7

PDF/A-2 was published in 2011 as “ISO 19005-2”. Based on PDF version 1.7, which has since been standardised as “ISO 32000-1”, it makes use of this version’s new features. This means PDF/A-2 allows JPEG2000 compression, transparent elements and PDF layers. PDF/A-2 also allows you to embed OpenType fonts and supports PAdES (PDF Advanced Electronic Signatures)-compliant digital signatures. One particularly important innovation is the “container” function: PDF/A files can be embedded within a PDF/A-2 document.

PDF/A-3: One more feature

PDF/A-3 has been available since October 2012. A PDF/A-3 document allows you to embed any file format desired – not just PDF/A documents. For example, a PDF/A-3 file can contain the original file from which it was generated. The PDF/A standard does not regulate the suitability of these embedded files for archiving.

Conformance levels: A, B, U

The different conformance levels reflect the quality of the archived document and depend on the input material and the document’s purpose.

  • Level A (Accessible) meets all requirements for the standard, including the logical structure of the document and its correct reading order. Text must be extractable and the logical structure must match the natural reading order. Fonts used must meet stringent requirements. This PDF/A level can usually only be met by converting born-digital documents.
  • Level B (Basic) guarantees that the content of the document can be unambiguously reproduced. Level B files are easier to create than Level A, but Level B does not guarantee 100% text extraction or searchability. It does not necessarily mean that the content can be reused without any problems. Scanned paper documents can usually be converted to PDF/A Conformance Level B without any extra work.
  • Level U (Unicode) was introduced along with PDF/A-2. It expands Conformance Level B to specify that all text can be mapped to standard Unicode character codes.

Nomenclature: PDF/A versions and levels are simply given one after another. A PDF/A-1b file, for example, is a PDF file for long-term archiving, of the first generation, with visually reproducible content.

< previousoverviewnext >

Tags: Conformance levels, ISO Standard
Categories: PDF, PDF/A