General comments
If a Web page uses scripts (e.g. JavaScript or scripts in Macromedia Flash content), and if the scripts affect any content displayed to the user, there should be equivalent text provided (by the page or by the script) that is accessible to a screen reader.
More on scripts.
If a Web page uses applets (e.g. downloadable Java applets), it should also contain the same information and functionality in an accessible format.
More on applets.
If a Web page uses other programmatic objects (e.g. Flash, Shockwave, RealAudio, or RealVideo content), or otherwise requires the use of plug-ins or programmatic support for the browser, the page should include a link to the plug-in or programmatic item required for accessing the content of the page and that plug-in or programmatic item must itself be accessible to people with disabilities. In other words, it should comply with 36 C.F.R. §1194.21.
More on plug-ins.
If a Web page includes links to .pdf (Adobe Acrobat's portable document format) files, those .pdf files should be ones which were created in a way that maximizes their usability for people with disabilities. In other words, they should comply with 36 C.F.R. §1194.21.
More on pdf.
Scripts
When authors do not put functional text with a script, a screen reader will often read the content of the script itself in a meaningless jumble of numbers and letters. Although this jumble is text, it cannot be interpreted or used. Rule l requires that text be provided that, when read, accurately conveys what is being displayed by the script.
For example, if a web page uses a script only to fill the contents of an HTML form with basic default values, the web page will likely comply with this requirement, as the text inserted into the form by the script will probably be readable by a screen reader. In contrast, if a web page uses a script to create a graphic map of menu choices when the user moves the mouse over an icon, the text (image) for each menu choice cannot be rendered to the assistive technology. Therefore the web site designer would need to incorporate redundant text links matching the menu choices. Determining whether a web page meets this requirement may require careful testing by the web site designer, particularly as both assistive technology and the JavaScript standard continue to evolve.
Applets
Applets are special programs written in Java, a computer language created by Sun Microsystems. Java applets are different from scripts (such as scripts written in Javascript!) because they are not included in the HTML content of the web page and are partially compiled to run faster on the user's specific type of computer (Windows, Mac, UNIX, etc.). Thus applets may be downloaded with a web page, rather than in it. Java applets, unlike content developed for plug-ins, do not require the addition of third-party software to operate, as long as the browser's computer supports Java (as most do) and has Java enabled. Most modern browsers can run applets.
Unfortunately, many browsers used by people with disabilities do not work with applets. In addition, while Sun Microsystems has incorporated accessibility features in Java, most Java developers do not make use of these features. Therefore, in order to make the content of applets accessible, web developers should provide text alternatives.
The <APPLET> tag for Java applets accepts an "alt" attribute, but it only works for browsers that provide support for Java. A better alternative for providing textual descriptions is to simply include the alternative text between opening and closing <APPLET> or <OBJECT> tags.
Plug-Ins
Plug-ins are third-party software added to a computer browser to allow the browser to use special content not normally available using just HTML. For example, the multimedia and streaming video (e.g. RealAudio, RealVideo) available from some information service web sites use plug-ins to provide real time broadcasts of radio and television programs. Adobe pdf is another example of the use of plug-in technology.
Web designers evaluating the accessibility of plug-ins should review the Access Board's section 508 rule as it applies to software, 36 C.F.R. §1194.21 (contained in: www.access-board.gov/sec508/508standards.htm).
Adobe Acrobat's Portable Document Format (pdf)
Many agencies have turned to Adobe Acrobat's portable document format (.pdf) to ensure a more controlled presentation of documents posted to their websites than is available with HTML. Documents created in pdf will appear identical on every computer monitor and on every computer printer. Page breaks, margins, fonts, and even graphics such as signatures, will appear the same as in the original document.
To view a pdf document, the Web user's computer must have the Adobe Acrobat Reader "plug-in" software. Unfortunately, even with the plug-in, pdf documents may not be accessible to assistive technology. Whether they are depends in part on how they were created.In general, pdf documents can be created in several ways and each method has separate implications for accessibility:
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Scanning a document into pdf creates a so-called "PDF Image Only" file that is essentially a graphic representation of the document and, like a photograph with no associated text, is generally unreadable by screen reader technology.
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Scanning a document into pdf and then running it through OCR ("optical character recognition") technology converts the text images into searchable text. Such documents must be checked carefully for accuracy, but can be accessible.
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Printing a file directly into pdf format converts the electronic information into a digital representation of the document that is somewhat readable to assistive technology.
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Writing a document inside Adobe Acrobat can also result in a document that is somewhat readable by assistive technology.
Web developers should try to use the last two methods of creating pdf files and should avoid the first method entirely. Adobe's accessibility site includes includes the latest recommendations for making pdf files accessible (http://www.adobe.com/enterprise/accessibility/main.html). Finally, agencies should be careful that non-text content be accompanied by text descriptions in pdf files. Agencies that choose to publish web-based documents in pdf should simultaneously publish the same documents in another more accessible format, such as HTML.
Department of Commerce Web Advisory Council (WAC)
U.S. Department of Commerce
Send questions and comments about this page to WAC@doc.gov
Page last updated October 12, 2010
- Alicia R. Sowah
Deputy Director of Digital Engagement
Gregory Johnson
Co-Chair, Web Advisory Commmitee
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