Guide to Guideline 2.4 Level 2 Success Criterion 1

2.4 L2 SC1

delivery unit

A set of material transferred between two cooperating web programs as the response to a single HTTP request. The transfer might, for example, be between an origin server and a user agent.

NOTE: This term was taken verbatim from Glossary of Terms for Device Independence.

NOTE: Placeholder for description of intent


Provide a table of contents

The table of contents serves two purposes:

  • It gives users an overview of the document's contents and organization; and

  • it allows readers to go directly to a specific section of an online document .

The table of contents typically includes only major sections of the document, though in some cases an expanded table of contents that provides a more detailed view of a complex document may be desirable.

The table of contents should provide links to section headings and sub-headings within the hierarchical structure of the document. Authoring tools or user agents may create tables of contents automatically, based on section headings in the document. Authors or users may be able to control how much of the document structure is displayed in the table of contents.

The table of contents may include many links and may extend over several screens. It may add significantly to the actual and perceived length of the document. This can create difficulties for people using screen readers and screen magnifiers as well as for people who use a keyboard or keyboard interface. Therefore, it is good practice to allow users to skip over the table of contents. This can be accomplished by using a section heading to mark where the Table of Contents begins and by providing a link that bypasses it. In some cases it may be helpful to place the Table of Contents in a separate document.


Using a site map to help users find content

Many Web sites, especially large sites with multiple sections and many pages, should offer users several ways to navigate the Web site. global or sitewide navigation bars make it easy for users to reach major sections of the site, while local or section-specific menus allow the user to find content within a particular section. Site maps provide an overview of the entire site. They may be helpful when the site is too large for the global navigation bar to include all pages. Site maps may be especially helpful for users whose disabilities make it difficult to remember where information is located or to understand how different parts of the site are related. People who use only a keyboard or keyboard interface may find it easier to enter keywords or phrases in a site-specific search engine than to scroll or tab through a long or complex site map.

The site map serves several purposes.

  • It provides an overview of the entire site.

  • It helps users understand what the site contains and how the content is organized.

  • It offers an alternative to complex navigation bars that may be different at different parts of the site.

There are different types of site maps. These include, but are not limited to, the following:

Editorial Note: The items listed below are drawn from the Glossary entry that defines alternate navigation mechanisms. Recent discussion on the mailing list has raised questions about whether all of these variants should be listed. They are presented here for review.

  • Site outline. The simplest and most common kind of site map is a text document with an outline that shows links to individual pages within each section or sub-site. Such outline views do not show more complex relationships within the site, such as links between pages in different sections of the site. The site maps for some large sites use headings that expand to show additional detail about each section.

Many users will benefit from site maps that provide more information about the organization of the site and relationships within it. Possibilities include, but are not limited to, the following:

  • Tree diagrams show each page as a box with a line that connects it to its "parent."

  • A cone tree is like a three-dimensional tree diagram. Branches spread out from each node, making a cone shape.

  • A disc diagram shows The organization of the site as a series of concentric rings, with the home node at the center.

  • A dome tree, a variant of the disc tree, gives a three-dimensional view of the site. The dome tree shows relationships between sections as connecting lines.

  • A hyperbolic map can provide a dynamic view of a large site. As the user focuses on a section of the map, the section becomes larger, as if it were viewed through a magnifying lens; the other sections become smaller but remain in view so that the user can still have an overview of the entire site. This is sometimes called a fish-eye view.

Graphical site maps must be legible to users with low vision, and must satisfy the requirements for text alternatives under Guideline 1.1. They must also be accessible to people using a keyboard or keyboard interface, as required by Guideline 2.1 L1 SC1.

Tools that automatically generate site maps are widely available at a range of prices. The resulting site maps, like site maps that are created manually, will be more effective when the site itself is well organized. Automatically generated site maps should be tested for accessibility before they are published.

Some users may be confused by site maps that list similar-sounding section and page titles for different areas of the site.


HTML techniques

other resources

  • Graphic Organizers page at the National Center for Accessible Curriculum provides a useful overview of different kinds of graphic organizers and their uses, plus a summary of relevant research on the effectiveness of graphical organizers for students with learning disabilities.

  • The Usability Glossary's definition of site map [@@ need escape char for amp for the uri]


Providing a search engine to help users find content

The search engine is an important part of a design strategy that offers users different ways to find the content they are interested in. For example, the search engine can help users find specific words or phrases that do not appear in navigation bars or in the page titles listed in the site map.

In order for the search engine to provide an effective navigation mechanism, the site must has keywords, META tags, and an accessible navigation structure, including informative page titles and section headings. In other words, techniques that are used to optimize search engine results for external searches also support internal search engines and aid accessibility in other ways.

The search form itself must be accessible.


General Techniques

HTML Techniques

Editorial Note: We may need an HTML technique about META description= and META keywords= as devices to support search engine optimization; these would be related to Guideline 2.4 L2 SC1.

other resources

NOTE: Placeholder

NOTE: Placeholder for Benefits section

NOTE: Placeholder for examples

NOTE: Placeholder for Resources section