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HTML Unleashed PRE: Creating Widely Accessible Web Pages |
Miscellaneous Modalities
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 n this last section, we'll discuss the
accessibility aspects of all other Web page elements and interfaces
that didn't fit into the "Text," "Graphics," "Layout,"
and "Forms and links" sections above.
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Documents using frames are really a scourge for disabled users
(and, as we'll see in the next chapter, for search engines too). It's
not that they're inaccessible in principle because of using a
non-conventional medium or something; in fact, a root page of a
frameset is nothing but a collection of links to frame pages,
although these links are expressed via FRAME tags instead
of conventional hypertext anchors.
Of course it is almost impossible for a blind person to really
use a framed page---more difficult, perhaps, than playing
chess without looking at the board. It's obvious, nevertheless, that
at least some use could be made from framed pages by letting
disabled users follow the FRAME references as though they were
the usual hypertext links. Unfortunately, to my knowledge no user agents
currently implement this functionality.
For screen readers, a framed page is an aggravated example of the
tabular layout (see "Tables" earlier
in the chapter) with all its undesirable consequences galore.
Other screen readers tend to treat each frame as a separate window,
so sometimes it may be difficult to force the program to switch to
another frame.
There exists, however, a method of making framed sites accessible
to people with disabilities by using the NOFRAMES tag. This
technique is covered in detail in Chapter 43, "Strategies
for Indexing and Search Engines." | |
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Just like images, audio and video clips are inherently inaccessible
to some categories of users. The methods of solving this problem are
also similar to those developed for images (see "Graphics" earlier in the chapter).
If an audio or video clip carries important information that you
want to be accessible to everyone, you should accompany it with a
transcript (for speeches, conversations, and so on) or by a general
description (for non-verbal sounds or scenes). As with alt
text for images, you should try to convey the information contained
in the clip, not meta-information about the clip itself.
For instance, indicating file size for large audio or video files may
be useful, but it doesn't belong in the alternative representation of
a multimedia clip: it's those who are able to view/hear
multimedia who may need this information, not those who are deprived
of the possibility.
Technically, a transcript or description can be located in a
separate page linked near the clip it belongs to. Also, as these types
of data are likely to be embedded using the OBJECT element,
you can use its alternative rendering capability: all content enclosed
between <OBJECT> and </OBJECT> will be
rendered only by those user agents that can't render the
OBJECT itself.
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These two web-related programming languages are often considered to
be something from the high-tech world of the latest graphic
browsers, unlimited bandwidth, and sophisticated interfaces.
It is true that only the major graphic browsers now support Java and
JavaScript, but this doesn't mean you must completely abandon
them for your pages to be universally accessible.
Java is not a tool for producing artful widgets for web pages; it
is a full-blown programming language with a great potential for
building effective and portable information processing applications.
Java applets can be used---and are used---for a multitude of
tasks that couldn't be performed with any other technology. There are
situations where the practicality of using Java is not in question;
what may be in question is how to make Java applications accessible.
The basic principles (alternative modalities, logical rather than
physical description of data) remain valid, but there are, of course,
quite a number of Java-specific recommendations. Thus, Java
accessibility is a huge topic, and an HTML book is perhaps not the
place to discuss it in any detail. For the latest developments in the
field of Java and JavaScript accessibility, refer to the site maintained
by Trace R&D Center.
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