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Re: Which A.T. uses the R.O.?

for

From: Chagnon | PubCom
Date: Aug 5, 2014 2:58PM

Thanks Olaf for the excellent detailed explanation. You confirmed what I
thought.

It appears that we still have some assistive technologies that use the RO
(z-order) rather than the tag order, but there's hope it will become
obsolete sometime in the future.

If anyone has a particular AT that uses the RO, other than braille keyboards
and printers and Kurtzweils, please let us know. I'm trying to document
which items use this.

To clarify for others on the list, "raw page description" is basically the
code written into the PDF file and it directly correlates to the sequence of
steps the user made to create the document.

When using MS Word to create a PDF, this sequence usually follows from
top-down and left-to-right, so the reading order (or z order) usually is the
same, top-down, left-to-right (ok, forget the tragic flaw in Word 2010 and
think instead Word 2013 which places anchored objects in the correct order).

The problems arise when PDFs are made from visually rich documents, like
those from Adobe InDesign, M.S. Publisher, and M.S. PowerPoint. In those
programs, the authors place items all over the place and not necessarily in
the top-down left-right order. And their sequence of mouse-clicks used to
create the document are all over the place, too. It's that sequence of
mouse-clicks (or placement of items like text blocks and graphics) that
don't follow a logical reading order at all.

Hence, really crazy reading orders (z-order) in the resulting PDF, even
though the tag reading order is just fine.

—Bevi Chagnon
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