February 13, 2014 5

Screen shot of the tags in the dl list in the attached PDF.A discussion on the WCAG listserv prompted me to think about lists.

What’s the difference between the HTML and PDF treatment of list content?

This short article contrasts HTML’s list tags with PDF’s standard structure elements for lists.

The article argues that PDF’s list model is more capable. As PDF provides accessibility-support via a generic mechanism, the portable document format is able to accommodate list semantics in a wider variety of scenarios than HTML.

There are two salutary reminders:

  • HTML does not define the scope of all possible document content; it simply defines itself.
  • PDF, first and foremost a page-painting system, encompasses pretty much any possible final-form “hardcopy” content. Happily, PDF’s approach to list structures can accommodate any sort of list one might choose to create.

A list is a list. It’s the list’s labels that contain the semantics.

Read Lists: Contrasting HTML with PDF