Please look at this draft; not for circulation yet.

Hello WAI Curriculum folks,

Please look over the draft below and send your comments to ij@w3.org, with
a cc to me, by the end of the day Wednesday, January 27 if possible.  

Please do not circulate this draft; we will have a final version within
about a week.

First though, here is a brief background & update:

Back in November at the Austin meeting we discussed that one of our key
priorities was to get out some chapter modules and/or educational
information on the HTML 4.0 accessibility improvements, and the people on
this list volunteered for an ad-hoc "curriculum" group to work on this.

You should have all gotten a "welcome to the ad-hoc curriculum group"
message on December 1, and I heard back from a few people individually
(thanks Helen, and Bert) with leads to publishers or writers.  But not much
has happened since on curriculum development, so I asked Ian Jacobs, one of
the editors of the HTML 4.0 specification, to draft this explanation of the
HTML accessibility improvements which you saw go out in mid-December on the
WAI Interest Group list.  Daniel helped, & I edited it a bit, and now
invite your editing.

The intent of this document is to be multi-audience; to neither assume
extensive technical background nor much background in accessible design,
but rather to be generic enough that technical or lay writers can adapt it
to their own audiences.  We'll also be using it as a reference piece for
some additional publicity on HTML accessibility improvements.

A further development since then is that the HTML Writers Guild has joined
the W3C and has offered to help the WAI get the message out (thanks Ann,
cc'd on this message!)

By the way, those of you who had also volunteered to help with a charter
for the Education and Outreach Interest Group should also see a message in
the next few days with a draft charter to review; or, if you hadn't signed
up to help with the draft charter, you'll see the official call for
participation come out on the WAI interest group list-serve within several
weeks.

Again, comments go to Ian Jacobs at ij@w3.org, cc'd to me.  (You can also
send to w3c-wai-curric@w3.org, if you are on it, but I haven't yet
confirmed if it can accept submissions from outside the list.)

Thanks,

Judy


Accessible HTML

The W3C Web Accessibility Initiative (<#ref-WAI>[WAI]) had a significant
impact on the design of <#ref-HTML40>[HTML 4.0], which became a W3C
Recommendation in December, 1997. Just as real-world accessibility
innovations have improved everyone's lives, WAI's requirements and
suggestions heightened the awareness of the HTML Working Group and enabled
them to design a superior language for all content providers, site
managers, and users -- not just those with particular functional
requirements related to disability.

While many people generally think of browsing as a primarily graphical
activity, many people browse with non-graphical tools, including:

Screen readers
Screen readers intercept code being sent to a monitor and direct the output
to speech synthesis or a refreshable Braille display.
Audio browsers 
Audio browsers read and interpret HTML (and style sheets) and are capable
of producing inflected speech output. 
Text-only browsers 
Some devices (including handheld devices with small character displays) may
only be able to display characters. 

HTML authors generally attempt to produce attractive, meaningful pages, but
prior to HTML 4.0, the insufficient means available to them had the
undesired outcome of making those pages inaccessible to users with
non-graphical browsers. Even if authors did want to create pages accessible
to users with audio or braille browsers, the cost of doing so was high
because it often meant producing and maintaining text-only versions of pages. 

Many of the features of HTML 4.0 inspired by accessibility concerns now
allow authors to design more attractive documents for a larger audience at
the same time as they eliminate the burden of managing multiple HTML
documents.

Style sheets

Without the proper tools, HTML authors have been forced to "misuse"
elements to design visually appealing documents. For instance, earlier
versions of HTML do not have a proper mechanism to indent a paragraph, so
many authors have resorted to using the BLOCKQUOTE element to indent text
even when there is no quotation. This is misleading for non-visual users:
when an audio browser encounters a BLOCKQUOTE element, it might expect to
read the enclosed text as a quotation; but more often than not, it
shouldn't, since the element has been misused for a presentational effect. 

The BLOCKQUOTE example demonstrates the misuse, for presentational
purposes, of an element intended to provide logical information. Many
similar traps seduce HTML authors: they use H2 or H3 to change the font
size of some text that is not a header; they use the EM element to
italicize text when in fact, EM is meant to emphasize text (often presented
with an italic font style, but rendered differently by a speech
synthesizer); they use lists for alignment, etc. 

Inversely, it is possible to use presentational elements to represent
logical structure. For instance, authors may use the PRE element to
preformat text in a way that conveys structure to a visually-oriented
audience, but will only confuse a person using a screen reader. PRE should
not be used to create tables of information; the new TABLE element serves
that purpose. Similarly, PRE should not be used to build ASCII images --
"ASCII art."  ASCII art, which presents an image made of positioned text
characters, is unintelligible to screen readers which render the characters
in a linear stream. Instead, authors should use real images, providing
<#alternate> textual descriptions of those images for users with non-visual
browsers. 

The above problems primarily arose due to the limited layout features of
previous versions of HTML. Style sheets -- fully integrated into HTML 4.0,
and increasingly implemented by the latest browsers -- provide a mechanism
to control layout.  Not only do style sheets give authors more powerful
tools to achieve visual and non-visual effects, they make HTML documents
more accessible. Now, authors may indent and align text without misusing
semantic elements such as BLOCKQUOTE, or inserting invisible images for
positioning. When authors remove presentation information from the HTML
markup of a document, users with non-visual browsers consulting those
documents don't have to sift through markup meant "for your eyes only." 

Furthermore, by removing presentation attributes from HTML documents and
specifying multiple style sheets for different media (these style sheets
are attached to HTML documents via the LINK element), authors make their
documents more manageable for a variety of purposes. HTML documents that
make good use of structural elements may be reused, along with their linked
style sheets, with virtually no modifications, and no copying over to
text-only versions.
 
Alternate content

A picture may be worth a thousand words to some people, but others need at
least a few words to get the picture. Authors should always provide
"alternate text content" that a non-visual browser may substitute for a
visual effect, including applets and scripts, images, and video and sound
clips.  This is especially important when an applet or an image conveys
important information. 

One of the most significant improvements to HTML 4.0 in the area of
alternate content comes from the new OBJECT element.  The OBJECT element
allows authors to include generic objects (images, video, sound, etc.) in
their documents. More importantly for accessibility, the OBJECT element
provides a mechanism for generically including alternate content. Embedded
OBJECT elements behave as follows: when an outer OBJECT's data cannot be
rendered, the next embedded OBJECT is rendered (and so on for multiple
embeddings). Thus, for every image, applet, etc., authors may specify two
OBJECT elements: one for the primary effect and one for the alternate text
content (this is just one reason for embedding OBJECT elements -- another
is to give user agents the possibility of rendering alternate
implementations of an object). The OBJECT element may also be used in
conjunction with the MAP element for more accessible image maps (see
href="#navigation"> navigation below). 

Note that alternate content mechanisms have an impact in areas other than
accessibility. Text content is useful for sighted users who have configured
their browsers not to display images (e.g., because their modem is slow) or
for those users who are "temporarily disabled," including users who want to
hear Web sites read aloud to them as they drive to work. 

Other HTML 4.0 alternate text mechanisms include the following: 
* The "alt" attribute allows authors to provide short textual descriptions
of images, image maps, form controls, and applets (not required if the
OBJECT element is used). 
* The "longdesc" attribute allows authors to provide longer descriptions of
complex images, tables, and frames. Authors write these longer descriptions
in an external document. 
* The "title" attribute may be used to annotate any element with a textual
description. Graphical browsers frequently pop-up this information when a
user pauses over an element with the mouse, but it is equally useful to
non-visual browsers.  

These attributes have many other applications as well.  For instance, the
"title" attribute may be used with the new ABBR (abbreviation) and ACRONYM
elements to indicate the expansion text of an abbreviation. Or it may be
used to provide a short description of an included sound clip. Or it may be
used to provide information about why a horizontal rule (the HR element)
has been used to convey a structural division (although authors can now use
the new DIV element in this case!). 

Easier navigation

Users with non-visual browsers frequently have difficulty navigating pages
that rely heavily on graphical cues. For instance, image maps with no
textual alternatives are next to impossible to navigate if you aren't using
a graphical browser. Links that make little sense without a broader context
(e.g., a link which simply reads "click here") present poor navigation
options, as do links whose text runs together and may be read as a single
link by a screen reader. 

HTML 4.0 includes several features to facilitate navigation: 
* For client-side image maps, the MAP element now allows authors to furnish
detailed textual explanations of links at the same time as they specify the
active regions of their image maps, eliminating the need to duplicate
information.
* The "title" attribute, when used with the A element, can be used by
authors to describe the nature of a link so that users may decide whether
to follow it. 
* The "accesskey" attribute allows users to activate links or form controls
from the keyboard. 
* The "tabindex" attribute allows users to use the keyboard to navigate the
links or form controls on a page in a logical sequence.
* The LINK element (specified in the header of a document) together with
the "media" attribute allow user agents to automatically load appropriate
pages for a specific target medium, making user navigation to those pages
unnecessary.

More meaningful markup

HTML 4.0 includes a number of features that enable authors to add more
structure to their documents. Highly structured documents are certainly
more accessible to users, but they also increase the efficiency of search
engines, document transformation tools, etc. The new elements include: 
* The ABBR and ACRONYM elements, which are particularly interesting to
speech synthesizers when used in conjunction with style sheets and the
"lang" (language) attribute. 
* The OPTGROUP element. Authors designing menus for forms may now break
down long lists of choices into logical groups. Such groups improve
navigation among menu options and reduce the burden of browsing (and trying
to remember) long lists of choices.  
* The FIELDSET and LEGEND elements. These elements allow authors to
organize form controls into semantically-related groups. 

Additionally, many elements and attributes have been added to make tables
more accessible: 
* The CAPTION element provides a description of the table. The "summary"
attribute may also be specified for a longer description of the table,
rendered by non-visual browsers. 
* Several elements have been added so that table rows and columns may be
grouped into logical sections without resorting to visual effects. 
* Visual browsers generally present a table as a grid of cells. The new
"scope" and "header" attributes allow authors to label their cells so that
non-visual browsers may render a table in a linear fashion, based on the
semantically significant labels. 

As you can see, the new features of HTML 4.0 allow content providers and
vendors alike to contribute to making the Web accessible to a much larger,
and very eager, audience.

References

[HTML40] 
The HTML 4.0 Specification is available at
<http://www.w3.org/TR/REC-html40>http://www.w3.org/TR/REC-html40. The press
release is available at
<http://www.w3.org/Press/HTML4-REC>http://www.w3.org/Press/HTML4-REC. 

[WAI] 
Please consult the WAI home page at
<http://www.w3.org/WAI>http://www.w3.org/WAI for HTML authoring guidelines
to improve your site design at the same time you make your pages more
accessible. 

Acknowledgments

Thanks to the many individuals and companies on the WAI mailing lists who
have contributed ideas to help bring about these accessibility
improvements. In particular, thanks to participants of the Web
Accessibility Initiative's HTML & CSS Review Working Group, which developed
many of the recommendations, and to the HTML Working Group, which
incorporated them. 
----------------
Please send comments to the authors:
Ian Jacobs (<mailto:ij@w3.org>ij@w3.org)
Judy Brewer (<mailto:jbrewer@w3.org>JBrewer@w3.org)
Daniel Dardailler (<mailto:danield@w3.org>danield@w3.org)

-------------------------------------------------------
Judy Brewer   jbrewer@w3.org     617-258-9741
Director, Web Accessibility Initiative International Program Office
World Wide Web Consortium (W3C)
MIT/LCS Room NE43-355
545 Technology Square, Cambridge MA 02139 USA
http://www.w3.org/WAI

Received on Sunday, 25 January 1998 18:04:00 UTC