W3C home > Mailing lists > Public > public-comments-wcag20@w3.org > December 2009

A test of the flexibility of WCAG 2.0 to adapt to a new situation presented by tagged PDF.

From: Wayne Dick <wed@csulb.edu>
Date: Fri, 11 Dec 2009 11:57:35 -0800
Message-ID: <4B22A42F.2000800@csulb.edu>
To: public-comments-wcag20@w3.org

I cannot read PDF effectively.  I have moderate
low vision (20/80 fully corrected) caused by
central retina damage.  This has been a lifelong
issue, and I'm an old hand at trying assistive

The problem is that PDF does not have an assistive
technology that permits individualized: (1)
modification of font-family based on element (tag)
type, (2) enlargement of letter, word and line
spacing for text and (3) variable enlargement
linked to element type.  These modifications are
important for many people like me (Moderate Low
Vision 20/70 - 20/160).  This need is well

I believe that one cannot claim conformance with
1.3.1 and hence at Level A in this case.  Here is
my logic:

1.	Criterion 1.3.1 (Info and Relationships) says:
Information, structure, and relationships conveyed
through presentation can be programmatically
determined or are available in text. (Level A).
Adobe claims the physical structure of tagged PDF
files do meet this.  I have no reason to doubt them.
2.	Accessing text in tagged PDF is closed to users
for all the necessary parameters I have mentioned.
3.	Text is part of information and expresses
relationships.  Characters (letters, digits and
punctuation) are central to reading.  Characters
in the wrong font are difficult to perceive.
Serifs cause visual complexity and reduce
perception of foreground.  Also, white space
expresses relationship.  In words space helps
distinguish letters, in lines space separates
words and between lines space indicates reading
sequence (Criterion 1.3.2).  The problem is this:
without enlarged spacing individual letters within
words and words in lines get lost or confused.
Small spacing between lines causes reading
information from the wrong line out of sequence,
the tracking problem.  All these semantic cues are
presented visually.  Since, 1.3.1 refers to
information, structure and relationships without
any qualification, I have always assumed that
1.3.1 applies to text.  I don’t mean to the
natural language meaning of text, just the
document structural meaning. Information that can
be programmatically determined.
4.	PDF has no accessibility support to enable the
modifications of text that my disability group
5.	Tagged PDF is a structured medium, so the
sufficient techniques that apply to tagged PDF are
in Case A of the Sufficient Techniques for 1.3.1.
  G140: “Separating information and structure from
presentation to enable different presentations,”
is part of this set of techniques.  All these
techniques must meet to satisfy Case A, but G140
has incomplete accessibility support for modifying
text presentation.
6.	Sufficiency is not necessity, so this does not
prove inaccessibility, but the only published
proof that tagged PDF is accessible is not
accessibility supported for G140.  Hence, tagged
PDF cannot use Case A of the sufficient techniques
for 1.3.1 to claim accessibility.  The only other
case published in the techniques document does not
7.	Tagged PDF provides the cues necessary to
support access to text, but there is no attainable
assistive technology that enables this access.
This excludes people with moderate low vision from
using PDF effectively.
8.	I apply Conformance Requirement 4: Only
Accessibility-Supported Ways of Using
Technologies: Only accessibility-supported ways of
using technologies are relied upon to satisfy the
success criteria. Any information or functionality
that is provided in a way that is not
accessibility supported is also available in a way
that is accessibility supported. (See
Understanding accessibility support.).  It follows
that the only reasonable way to post PDF at this
time and claim Level A support is to include an
alternative accessibility support.

When WCAG WG developed Criterion 1.3.1 and
technique G140, I doubt you ever envisioned a
medium that would enable programmatic
determination at all levels, and would not provide
the accessibility support needed to change
presentation of text in necessary ways.  Now we
have tagged PDF, and it falls exactly into that

You made WCAG 2.0 adaptable to changing
technology.  Tagged PDF is such a new technology.
  It is a qualitative improvement over original
PDF.  You put all that work into generality to
accommodate cases like this.  You did not write
1.3.1 saying "Information, structures and
relationships must be programmatically determined
... at the tag level only.  There was no
qualification of information, structure and
relationships.  That is good because it left this
criterion applicable to text as well as tags.  As
I have shown, the text nodes associated with tags
also contain information and relationships that
are critical to understanding.

There alternative media that enable text level
alteration of presentation to the individual user.
  HTML with CSS is perfect.  Most word processors
have a style template concept that enables simple
conversion from one visual presentation to
another.  Both are system level objects that can
be used for reading.

My question is this.  Regarding this new category
of medium:Can a medium claim Level A conformance
if: (1) includes programmatic access to
information, structure and relationships, but (2)
has no supporting technology to change text
presentation to meet the needs of a well known and
large group of people with disabilities? Does
Conformance Requirement 4 apply?  Also, does 1.3.1
apply to the syntactic indicators of structure and
relationships apply to text within elements?

I personally thought I was protected by 1.3.1.  If
1.3.1 does not apply, but I cannot use the text
with any known assistive technology does 1.1.1
fail? Is such a medium effectively non-text with
regard to accessibility support?

I would like to conclude with some minor points.
People with moderate low vision usually can see
headings.  We usually don’t need alternative text.
  Most of us like to use a mouse.  We just cannot
see the normal, most important, text.  Programs
like JAWS are disorienting because we depend on
the reduced sight we have, and even the lowest
level of chatter disrupts the concentration we
need to use our compromised vision.  Zoom
technologies rob us of our visual map of the page.
  HTML and many word processors provide us the
typographic control we need to change the
presentation to meet our needs.  A medium that
does not enable these users to change presentation
in the way they need, individually, excludes us,
and I think we are excluded because 1.3.1 and G140
are not fully supported.

I request that (not G140) be made a failure case 
for 1.3.1.  This technique should be necessary. 
To my mind 1.3.1 always was meant to give the 
freedom to change presentation - to a usable 
format: non-visual or visual.

To appreciate the needs of moderate low vision see:


Wayne Dick
Received on Friday, 11 December 2009 19:58:17 UTC

This archive was generated by hypermail 2.4.0 : Friday, 17 January 2020 19:14:52 UTC