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About the contributor
Duff Johnson

A veteran of the electronic document space, Duff Johnson is an independent consultant, Executive Director of the PDF Association and ISO Project co-Leader (and US TAG chair) for ISO 32000 and ISO 14289.
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.

A PDF Page Is a Painting

This article attempts to explain the concept of “reading order” in PDF files. Why is this necessary?

  1. Users are often frustrated by inconsistent and often illegible results when trying to read PDF files on mobile devices, search for PDF content online, or when using assistive technology (AT).
  2. Those tasked with ensuring accessibility or Section 508 compliance often focus on objects rather than logical structure, thus missing the mark.
  3. Software developers are (understandably) confused by “reading order” as presented in today’s PDF Reference (ISO 32000).

Many have come to use the term “reading order” as functionally synonymous with the logical order provided by PDF tags, but this interpretation is incorrect.

A screen-shot showing a simple example of how painting order and logical order may differ.

The PDF Paintbrush

When you create a PDF, you’re painting a picture. Your “paintbrush” is the combined effect of the software used to create the source document and the software you’ve chosen to convert your source document into PDF.

Like brushstrokes, each character, each line and each image is created independently, but interact to produce particular visual effects. On a PDF page, objects are connected by a coordinate system and little else. There’s no logical connection between the letters comprising a word; characters simply happen at a series of locations on the rendered page.

As originally designed, PDF is a system for painting on a page. There’s no innate concept of words, sentences, paragraphs, columns, headings, images, tables, lists, footnotes – any of the semantic structures that distinguish a “document” from a heap of letters, shapes and colors. PDF is fundamentally about how the document appears on the page, not how it looks when abstracted from the page.

(Originally posted on appligent.com. Read the rest of the article there)


Tags: accessibility, logical order, logical structure, reading order
Categories: PDF, PDF/UA