HTML Unleashed PRE. Creating Widely Accessible Web Pages: Miscellaneous Modalities

Frames

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."

Audio and Video

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.

Java and JavaScript

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.