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Re: Z-Order and Tag Order Need to Match?

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From: Duff Johnson
Date: May 27, 2020 4:48PM

Hi Lisa,

Content order and logical reading order are "separate" in PDF because the technology is obliged to represent content for different purposes. Rendering (e.g., printing) is a different purpose than accessibility, for example, and often requires ordering of content for processing purposes that differs from logical reading order. PDF was originally designed for maximum fidelity in print. Accessibility considerations were only addressed in 2000 with the addition of the Tagged PDF feature to the format.

In 2020 the difficulty is not in the format but in the software. Unfortunately it remains the case that...
PDF viewer developers don't do a great job of supporting tagged PDF in many cases. This is simply a business decision.
Users continue to use software that doesn't understand tagged PDF instead of seeking out and demanding better.
Authors continue to author content without consideration for semantics (e.g., use tab stops instead of table structures, etc.)
I'll beat my usual drum once again: if you want better PDF support, complain to those who make your software. Demand better support for Tagged PDF. In 2020 there's simply no excuse.

Duff.

> On May 27, 2020, at 18:30, Paul Rayius < <EMAIL REMOVED> > wrote:
>
> As per ISO 32000, one of the intents of PDF is that the "accessible layer" and the visual layer are independent of each other.
>
> Paul Rayius
> Director of Training
> CommonLook
>
>