Longtime readers will be aware of my interest in PDF accessibility. In furtherance of that interest, I work with the PDF/UA Committee – very much a happy ship, in stark contrast to a comparable working group. We are presently dealing with the issue of tables in accessible PDF. As our esteemed leader Duff Johnson (no relation) puts it,
The Committee requests that interested parties submit examples of “absurdly complex” tables to the Committee for review. In particular, we are interested in tables that cannot be adequately described using the current 1.6 Specification elements and attributes.
Yes, this is your chance to VENT about hideously complex tables you have been stuck with. But cast your net wide, please: Any source will do, including print, where we often find tables that simply cannot be rendered in HTML. PDF’s table tags and attributes are similar to, but not as extensive as, HTML’s. It is my intention to make the PDF spec for table accessibility better than reality and assuredly better than HTML’s.
To do this, we need to account for worst-case scenarios and for different uses of tables. For the latter, several come to mind:
- Zebra tables
- Tables with show/hide functions (so that only some rows are displayed on command)
- Tables with embedded headers (e.g., many columns of scientific results broken up by years, each of which year is a header spanning all or most of the columns)
- Mixed-writing-direction languages. (Actually, getting everything to work just as well in right-to-left and vertical writing systems is half a lifetime’s work right there)
- Images as headers (previously disputed as even possible by another working group; I guess they never read Spy)
- Character alignment, as with financial tables, where decimal points, parentheses, and dashes have to occur in certain columns
- Enumeration of list items (including the use of specific start points and jumping over certain numbers)
You can also write in with what you want a table specification to do even if nothing you know of does it already. You can leave a comment on the PDF/UA blog (short for “Web log”), mail things in to Duff, and preferably write your own posts and tag them with complextable.
Perhaps interestingly, I have a table up with nearly every known HTML accessibility feature, all of which added 27K to the file size with no demonstrable benefit. (And I dearly needed enumerated table rows.)
Update
(2006.01.27) I produced a list of examples of stupendous HTML tables. I also found some relevant PDF examples.