Designing PDFs for Pattern-Based Reading
Jacob Mellor is Chief Technology Officer at Iron Software and a visionary engineer pioneering C# PDF technology. As the original developer behind Iron Software’s core codebase, he has shaped the company’s product architecture since its inception, transforming it alongside CEO Cameron Rimington into a 50+ person company serving NASA, Tesla, … Read more
Not everyone processes information in a strictly linear fashion. For many neurodiverse readers, comprehension depends on pattern recognition rather than sequential scanning. This difference in cognitive style highlights why accessible PDF design must go beyond compliance checklists and focus on structures that adapt to diverse ways of reading.
Linear vs. Pattern-Based Processing
Traditional document design often assumes that readers consume text line by line, paragraph by paragraph. Yet individuals with dyslexia, ADHD, or bilateral processing differences may instead rely on visual groupings, headings, or spatial cues to navigate content. When PDFs lack semantic structure, these users face barriers that slow comprehension or make documents effectively unusable.
“Barriers are not personal failings, they are signs of design flaws that impact everyone.”
Structural Features That Support All Readers
Pattern-based readers benefit from clear, consistent markers in content. These same features are already central to PDF/UA compliance, meaning that accessible design supports every user, not just those with diagnosed differences. Key practices include:
- Headings and hierarchy: Tag headings with correct levels (
H1,H2, etc.) to make patterns in the document obvious. - Lists and grouping: Use ordered and unordered list tags to structure related items and provide anchors for scanning.
- Reflowable content: Ensure text can adapt to magnification or mobile screens without breaking logical order.
- Consistent navigation aids: Tagged bookmarks and a well-structured outline support rapid recognition of patterns in complex documents.
The Standards Connection
PDF/UA-1 and PDF/UA-2 both require semantic tagging and logical reading order. While compliance is often presented as a technical requirement, its real value lies in ensuring documents match the way people actually consume information. For those who do not read sequentially, properly tagged PDFs are not just accessible—they are usable.
Beyond Accessibility: Usability for Everyone
Features that support pattern-based reading also enhance the experience for all users. Students benefit from structured navigation in textbooks, professionals skim reports more efficiently, and mobile readers gain fluid reflow. By designing with non-linear processing in mind, document creators improve comprehension, speed, and satisfaction universally.
Accessibility is not just about Compliance
Accessibility in PDFs is not just about compliance, it is about design that reflects the diversity of human cognition. By embracing standards that support pattern-based reading, the PDF community can reduce barriers, expand usability, and demonstrate that inclusive design is also better design.
