The presentation at ICCHP 2012 shows why validity and semantics matters for a PDF/UA evaluation concept and how an automated checking tool can address this. In or-der to translate machine-testable requirements into checking criteria a special query language is developed called PQL (PDF Query Language). PQL will be implemented in PDF Accessibility Checker PAC 2, the first and free PDF/UA compliance checker crowd-funded by the foundation “Access for all”.

1. Validity and Semantics - Two Essential Parts of a Backbone
for an Automated PDF/UA Compliance Check
Markus Erle (Wertewerk) / Samuel Hofer (xyMedia)
13th International Conference, ICCHP 2012 - Linz, Austria, July 2012

2. Agenda
1. Starting Point
2. Our Approach and Results
3. The Impact and Future Work

3. 1.
Starting Point

4. 3 Main Questions
• How important is validity for accessible PDF
documents?
• How can the document structure be checked even by
users with basic accessibility knowledge?
• How can the PDF accessibility checker (PAC) be
improved to a PDF/UA Compliance Check?

5. 2.
Our Approach and Results

6. Is Validity relevant for Accessible PDF Documents?
• PDF/UA emphasizes validity as an essential
requirement
• validity can help to check a document
automatically (at least some aspects like the tag
syntax)
• without validity a PDF document may not be
compatible „with current and future user agents,
including assistive technologies“
(WCAG 2.0, success criteria 4.1.1)

7. Is Validity relevant for Accessible PDF Documents?
• PDF/UA emphasizes validity as an essential
requirement
• validity can help to check a document
Yes!
automatically (at least some aspects like the tag
syntax)
• without validity a PDF document may not be
compatible „with current and future user agents,
including assistive technologies“
(WCAG 2.0, success criteria 4.1.1)

8. How to check the Validity of the Syntax?
• special tool is necessary
• we developed a new query language called PQL
(PDF Query Language)
• PQL enables to select objects from a PDF
document by a variety of criteria
• PQL allows to define checks which validate the
PDF structures

9. How to check the Validity of the Syntax?
• special tool is necessary
• we developed a new query language called PQL
With PQL!
(PDF Query Language)
• PQL enables to select objects from a PDF
document by a variety of criteria
• PQL allows to define checks which validate the
PDF structures

10. How to Support an Easy Check for Semantics?
• Semantics are an essential requirement for
accessible PDFs
• the evaluation of the document structure
according to correct semantics cannot be
performed by automated tools
• a special preview - „screenreader preview“ - can
support the evaluator

11. How to Support an Easy Check for Semantics?
With a
• Semantics are an essential requirement for
accessible PDFs
•
Screenreader
the evaluation of the document structure
according to correct semantics cannot be
performed by automated tools
•
Preview!
a special preview - „screenreader preview“ - can
support the evaluator

12. 3.
The Impact and Future Work

13. PDF Accessibility Checker 2
• The foundation „Access for All“ with support of the
PDF Association initiated a crowd funding for
realizing PAC 2 as a free available and easy-to-use
PDF/UA compliance check
• It is based on PQL and contains a validity check and
an improved preview function
• A first version will be downloadable during the
fourth quarter 2012

14. Thank you!
Feel free to ask questions!
http://www.access-for-all.ch/en/pdf-lab/pdf-
accessibility-checker-pac/donation-pac-2.html