Accessibility
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Accessibility and Your Content
The goal of this document is to give you a quick jump start on knowing what you as a content provider can do to ensure accessibility as defined by the W3C's Web Content Accessibility Guidelines (WCAG).
If you want a thorough understanding, go to the excellent Penn State ITS guide to accessibility. Where appropriate, this document will simply reference that.
If you are really curious -- and ambitious -- read the quick reference to W3C's Web Content Accessibility Guide.
This document is geared toward sites within a content management system and in particular Plone sites. While there are some Plone-specific notes below, this information applies regardless of the CMS you are using.
Many of the page elements are controlled by the templates within your content management system. If you are a site manager or developer, this document can help you build (or modify, if necessary) your site's templates to adhere to accessibility guidelines. You should definitely read the ITS guide to accessibility referenced above and in particular, see the Advanced Web Design section of the ITS Accessibility Guide checklist.
Following are some of the things you should do.
Provide text alternatives for any non-text content
- Images - For images, this means providing alt attributes to your image tags. Those tags should be descriptive but concise and semantically useful. In Plone, the title of the image you upload becomes the value of the alt attribute, so create a good title.
- Audio and Video - Alternatives should be offered for pre-recorded video and audio in the form of captions or scripts. In the case of video, captions are preferred.
- Charts and graphs - Charts and graphs should have either an alt attribute or a longdesc attribute. Longdesc enables authors to provide a more detailed explanation of the content and can actually point to a file that holds that description. Also, beware of color coding the chart as that can be inaccessible to a user with color blindness.
- Decorative elements - If non-text content is pure decoration, is used only for visual formatting, or is not presented to users, then it should be implemented in a way that it can be ignored by assistive technology (e.g. images that have no meaning should have an empty alt tag like this: alt="").
Use Header Tags
Use header tags (h1 ...h6) to define logical blocks of content. In Plone, the editor gives users a heading and one or more subheadings to apply these elements. In addition to the formatting enhancements, these serve as indicators of information hierarchy within a document.
Links
A link should be text that describes the page to which you are linking. Avoid "Click Here" links.
See the PSU accessibility guidelines for a more detailed explanation.
Using Tables
Table headers, the scope attribute and the caption tag are necessary to make a table accessible. The summary attribute for simple tables, but can increase the comprehension of more complex tables for people using screen readers.
Table headers help screen readers parse the data in your table. You should include a scope attribute on the th tags (e.g. <th scope="col">) to define how the headings relate to the data.
A caption tag within the table element should describe the table contents.
A summary attribute is placed within the table tag and can clarify the organization of the table or provide a quick summary of results.
Marking up a table correctly will most likely require the content provider (or site administrator) to edit the HTML directly. WYSIWYG editors typically won't address all of these issues.
