The World Wide Web Consortium recently approved new accessibility guidelines. Passed in December 2008, the new "Web Content Accessibility Guidelines 2.0" is now the official recommendation for web accessibility for the disabled. This new WCAG 2.0 document, a welcomed update, replaces the WCAG 1.0 W3C (World Wide Web Consortium) recommendation of 1999.
This article is part one in a series discussing the impact of WCAG 2.0 on your website.
The new web content accessibility guidelines are designed around four fundamental principles:
- Is it perceivable?
- Is it operable?
- Is it understandable?
- Is it robust?
A document (or, web page) is accessible if it meets all four criteria, regardless of the abilities of the users, the tools they are using, and the technology used to create the document. In ecommerce, practical accessibility means only one thing: Can all visitors learn about and order your products?
For most users, perceivable content is visual. Your visitors view video clips, see images of your products, and read your descriptive texts. Perceivable content applies to the visual aspect of your website. But other aspects include providing a version of your content that is available for users who require other modes of sensing it.
That sounds complex, but all it really requires is that information be provided in a machine-readable text format. Computers can easily and efficiently take text and convert it into Braille or audio, but they can't work with graphics, video, or audio in nearly as effectively.
These later formats must be made available in a "text equivalent," which provides the meaning of the content it represents. It's more important to accurately represent the meaning than it is to reproduce text by rote.
Alternative text, when interpreted by a screen reader or other alternative method, will generally lose any impact conveyed by typography or other complex layout techniques used in graphics or video. This may mean that text taken literally from an image makes little sense; a paraphrase of the information might be more useful to the end user. If the text makes sense when read out of graphical context, you're going to be just fine. If not, you'll want to revise that text for your alternatives.
Remember, too, that accessibility isn't limited to those who can't see. It also applies to those who are color-blind, or to those with reduced vision.
Color Contrast Guidelines
WCAG 2.0 includes some good news for designers: The color contrast ratio has expanded. Although WCAG 1.0 did not actually specify an algorithm for color contrast comparison, the most commonly used guidelines were fairly restrictive. This isn't really the place for a discussion of the specific rules describing color contrast ratios, but suffice it to say it is a good idea to avoid low color contrast.
Allow for Varying Text Sizes
Text size has long been a major concern for visual users. With modern browsers, it's rare to encounter a site where text size cannot be modified by the user – but this doesn't make it an issue you can ignore. One of the significant changes in WCAG 2.0 is that, rather than dictating a particular size or presentation for your text, the document requires that a mechanism be available which will allow your text to meet accessible characteristics.
Keep it Linear
Not all perceivability issues are obvious. For example, when a user accesses a site using certain types of equipment, including screen readers and some mobile devices, the linear sequence of the content on the page may be changed. To help these users, make sure your text is structured to sequentially flow on these external devices. Avoiding the use of tables can greatly help with this.
Testing your website using any tool which re-renders the site content in a linear order is an excellent way to examine for sequencing problems. For websites built using the table element only – as a structure for tabular data – simply disabling cascading style sheets will quickly expose any problems.
If a site does make use of the table element for layout, this does not automatically mean that the site is inaccessible. However, the layout must be checked to see whether it follows a meaningful sequence. This can be done using a tool such as WAVE by WebAim. After running your test, choose “Structure/Order View” on the results page to identify the numeric reading order of each cell of the table.
Summary: Perceivable Content
Addressing every circumstance in which content can be perceived is a challenging task. WCAG 2.0 explains how content can become a problem, rather than dictating how the content should be presented. However, the ability to perceive the content is just the first step towards achieving accessibility. Even if a prospective buyer can easily perceive the link to purchase an item, it is a moot point if they can't make their way through your shopping cart.
In the next article, we will discuss the second principle of WCAG 2.0: Operability.