Among the greatest contributions of WCAG 2.0 to the cause of improving electronic content accessibility are 4 Principles and 12 Guidelines. These concepts underlie WCAG 2.0s Success Criteria; they are timeless statements that will shape the technical discussions about implementing accessibility in electronic content for decades to come.
Applying WCAG 2.0s Success Criteria to non-web technologies offers some challenges, a fact thats readily apparent when one considers the case of PDF. As Adobe Systems put it in their recent blog post:
PDF/UA defines the technical specifications to enable PDF documents to meet WCAG 2.0, but WCAG 2.0 has additional requirements which require an authors attention.
In a recent series of articles posted on his Logical Structures blog, NetCentric Technologies President and PDF Association Vice Chairman Duff Johnson discusses a seminal question in electronic content accessibility: the correct use of headings. He goes on to use this example to unveil some of the distinctions between WCAG 2.0 and PDF/UA.
In the first article, Heading Levels: Navigation or Decoration Johnson exposes the distinctions between the definitions of heading in HTML and PDF. After discussing how we collectively arrived at this point, he argues that PDF/UAs requirement for valid heading structures is appropriate in PDF because many PDF use-cases cause assistive technology users to depend on document structure for navigation.
In his second article in the series, Defining Heading in HTML and PDF, Johnson reviews in detail the technical definitions of headings in HTML and PDF in order to understand their role in WCAG 2.0. He goes on to suggest that Success Criterion 1.3.1 should be read as normatively requiring correct heading structures, at least in the use-cases (longer and complex documents) common to PDF.
Johnsons third article asks, What follows WCAG 2.0? He points out that while WCAG 2.0 has so far chalked up important regulatory support actual software implementations are lacking. The conclusion makes the point that technology-specific standards are more attractive to implementers while offering more consistent and interoperable results than is likely following WCAG 2.0 alone.
The closing article of this four-part series is an introduction to PDF/UA in non-technical terms. The piece provides five easy-to-understand reasons why PDF/UA matters in terms that make sense to end users.
Read all four articles on Duff Johnsons Logical Structures blog.