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[Irl-dean] Accessibility of PDF Format Resources?

Joshue O Connor joshue.oconnor at ncbi.ie
Mon Nov 27 10:41:56 GMT 2006


Barry McMullin wrote:

>  So it's really an issue
> with a particular product for authoring accessible (tagged) PDF
> rather than intrinsic to accessible PDF (as opposed to HTML). I
> guess that for some (most?) products that help "automate" the
> authoring of accessible HTML, then essential similar
> considerations would also apply?

Yes, I suppose that is a reasonable statement to make. Its not
necessarily that PDF itself is flawed, user agent support aside for the
moment - but due care and attention must be payed to the process of
creating accessible content.  being able to do this *correctly* does need a
certain skill level or knowledge on the part of the author.

> we surely need to carefully distinguish the technology
> of PDF from any particular vendor or product? 

Its strange for me to think of them as two separate things as I have
always associated PDF with Adobe (and think I always will).

> it is licensed for use on a royalty-free basis;
> and indeed there is now a substantial economy of both open and
> closed source developers and vendors of products which support
> PDF.  But if we take that stance seriously - that it really is an
> "open" technology, with multiple competing suppliers - then it is
> important to keep discussion of the technology separate from
> discussion of particular products and vendors.

For me even though it is licensed for royalty free use by both authors
and end users, its still an Adobe product and I think that will always
colour the discussion - but I agree with you.
I never considered it an 'open' technology though.

> I was commenting exclusively about the case where a public sector
> organisation is endorsing or encouraging (or perhaps even
> requiring?) their *customers*, or *clients*, etc. to use some
> particular tool or product or vendor, in order to avail of their
> services.  I think that is a completely different matter; in
> general, I would say it is a fundamentally anti-competitive
> practice, and should be avoided wherever that is at all possible.
> 

That process seems to be viral in that if one department starts to use a
particular technology it will quickly spread to others. This is often  a
process that is not examined in detail but I guess happens because everyone
else is doing it. Its only when authors hit a wall with the technology
(find out that a
large chunk of the audience can't access it) that they need to back
peddle and ask 'does this do what we need it to do".

> The particular product in question is, of course, the Adobe
> Acrobat Reader. As far as I can see, it seems that public bodies
> think it is somehow OK to selectively promote or endorse this
> just because Adobe offers it for "free".

Well the fact that Adobe developed the reader and then distributed it for
free is a big part of the success of PDF. If we all had to pay to view
PDFs it would be a different story.

>  Adobe is still a commercial enterprise, and the
> distribution of this product for "free" is still a commercial
> activity quite deliberately designed to give it leverage in the
> market. 

Absolutely. Very clever really.

>  But even aside from this: distribution
> of their reader functions directly as a device for promoting or
> advertising their other non-free products such as authoring tools
> etc.  And I have no problem with any of that, in itself: I just
> don't think that public bodies have any defensible role to play
> in *assisting* Adobe with this particular, clearly commercial,
> activity.

Thats a very interesting point. I never considered it from this angle
and I guess that you are right. PDF does come as a 'package' really, even
though the first look is through the freely distributed player. Its
telling that complex/detailed manipulation and tagging of PDF is only really
possible through Adobe products like Acrobat Pro, even though there are
plug ins for popular applications and even open source alternatives, I
don't think any of then offer the same degree of control as the
*expensive* Adobe
products (not that I am aware of). This is obviously by design - so
Adobe can sell more products.
interesting points Barry.

> And PDF of the encrypted/DRM variety? Well, there are many
> *other* problems with that, but it surely can't be regarded as an
> "open" technology in at all the same sense as non-encrypted
> PDF. So for that reason alone I would say it is quite unsuitable
> and inappropriate for use in any interaction between public
> bodies and their clients or customers.

I have had some discussion with Adobe developers about this on another
list and they say that access to screen readers *is* enabled by
default, even with basic encryption activated - the author however must
be aware that *higher* levels of encryption will lock down
assistive technology access, hence the dialogue box for "allow
access[...]"  IMO It sends a confusing message to the author.
So *some* higher security features come at the expense of accessibility
but not low level encryption? But is that enough for you security needs
and I don't like a model where you give authors the ability to over ride
user access in favour of increased security.

There are other approaches however, one which is via Certificate based
encryption, embedded in the PDF, so only
authorised persons can access the content, and the other is via Adobe
Bridge Server [1], which works along the line of server side keys which
need to be downloaded in order to shake hands with the client and open
then document. This works through extensions that the client needs to
have installed on their machine to access the content. So its a heavy
server/permission dependent approach.

Policy server via Life Cycle has recently being updated [2] without the
need to download and install extensions. As an aside - the new document
centre is a pure Flash interface, that repeatedly crashes my browser
(Firefox) whenever I have tried to check it out.

> OK, this has drifted rather far from considerations of
> accessibility for people with disabilities; but it is not
> completely irrelevant either. 

Viva la drift.

Josh

[1] http://www.adobe.com/products/server/policy/
[2]http://dc.adobe.com/





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