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Accessibility on the web has been an issue for over a decade, and it remains a crucial--but often overlooked--element of web design. Instructor Zoe Gillenwater explains the concept of accessibility as it applies to the web, and describes how it affects the audience. She also covers how to set up accessibility testing, and how to apply accessibility principles to new and existing sites using standards-compliant markup and CSS. Exercise files accompany the tutorials.
>> The web accessibility law in the U.S. is called Section 508. We'll go over the details of what each of its rules means and how to comply with it in our later movies. But first let's get a quick overview of what it's about. Section 508 is a U.S. accessibility standard that's mandated by law, part of the 1998 amendment to the rehabilitation act. Its rules apply to all federal agencies when they develop, procure, maintain or use electronic and information technology. The agencies must give disabled employees and members of the public access to information that is comparable to the access available to others.
Subpart B of Section 508 deals specifically with web accessibility. And it's made up of 16 rules. The first says a text equivalent for every non-text element shall be provided, e.g. via alt, longdesc or in element content. This rule is related to images and the information that images provide. Its goal is to make the information and the images accessible to people who cannot see the images. In later movies, we'll talk about the methods for doing so that are briefly mentioned in this rule. The next rule is equivalent alternatives for any multimedia presentation shall be synchronized with the presentation.
This rule pertains to captioning of multimedia presentations and making sure that they are accessible to people who have auditory problems. Rule C states web pages shall be designed so that all information conveyed with color is also available without color. For example, from context or markup. This rule benefits people who have colorblindness or other visual problems. Rule D, documents shall be organized so they are readable without requiring an associated style sheet. Throughout the movies in this title, we'll be talking about how to use CSS to style your pages.
But we'll always make sure that the pages can be read without these styles. This is related to the idea of progressive enhancement that we talked about earlier. We'll create a base markup for the page that can be read by a variety of devices. Then we'll add the styles on top for those who can take advantage of them. Rule E, redundant text links shall be provided for each active region of a server's side image map. Currently, image maps are almost entirely client side. And we'll talk about how to make those image maps accessible later. Rule F talks about these client side image maps and says, client side image maps shall be provided instead of server side image maps, except where the regions cannot be defined with an available geometric shape.
Rule G says row and column headers shall be identified for data tables. Tables often contain large amounts of complex information. And it's important for there to be markup that tells different browsers and other devices what pieces of data are related to other pieces in that table. Rule H states markup shall be used to associate data cells and header cells for data tables that have two or more logical levels of row or column headers. This is related to the previous rule. And again, we'll talk about it later in our movies on tables.
Rule I says frame shall be titled with text that facilitates frame identification and navigation. Again, this is a rule that is somewhat out of date, as frames are rarely used in websites today. Rule J, pages shall be designed to avoid causing the screen to flicker with a frequency greater than 2 Hz and lower than 55 Hz. This is another rule that is somewhat out of date. It applies mostly to web pages that used to use the HTML tag blink. A text only page with equivalent information or functionality shall be provided to make a website comply with the provisions of this part.
When compliance cannot be accomplished in any other way, the content of the text only page shall be updated whenever the primary page changes. This technique of creating the text only page has been very popular with some organizations when they're trying to make their websites accessible. However, it has a number of problems. And so we'll talk about those in a later movie. Rule L says when pages utilize scripting languages to display content or to create interface elements, the information provided by the script shall be identified with functional text that can be read by assistive technology.
This is designed to make sure that people who are using assistive technology can fill out forms successfully. And we'll talk about those techniques in a later movie. Rule O, a method shall be provided that permits users to skip repetitive navigation links. Having to hear that same navigation read on every page can be a real problem. So we'll talk about how to create skip navigation links later. Rule P, when a timed response is required, the user shall be alerted and given sufficient time to indicate more time is required. This is another rule that applies to your scripting practices.
So those are the 16 rules of Section 508 that all federal agencies and people who have federal funding must comply with. Again, we'll talk about the techniques and more of the details of what these rules are meant to accomplish in later movies. Next, we'll talk about another web accessibility standard called the web content accessibility guidelines.
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