Techniques for Web Content Accessibility Guidelines 1.0

Abstract

This document is the gateway to a series of related documents that provide techniques for satisfying the requirements defined in "Web Content Accessibility Guidelines 1.0" [WCAG10]. This series includes:

1. "Techniques for Web Content Accessibility Guidelines 1.0", the current document, which is the gateway to the other documents.
2. "Core Techniques for Web Content Accessibility Guidelines 1.0" ([WCAG10-CORE-TECHNIQUES]), which discusses the accessibility themes and general techniques that apply across technologies (e.g., validation, testing, etc.).
3. "HTML Techniques for Web Content Accessibility Guidelines 1.0" ([WCAG10-HTML-TECHNIQUES]), which provides examples and strategies for authoring accessible Hypertext Markup Language (HTML) content.
4. "CSS Techniques for Web Content Accessibility Guidelines 1.0" ([WCAG10-CSS-TECHNIQUES]), which provides examples and strategies to help authors write Cascading Style Sheets (CSS) as part of accessible content design.

Status of this document

This version has been published to correct some broken links in the previous version.

The 6 November 2000 version of this document is a Note in a series of Notes produced and endorsed by the Web Content Accessibility Guidelines Working Group. This Note has not been reviewed or endorsed by W3C Members. The series of documents supersedes the 5 May 1999 W3C Note "Techniques for Web Content Accessibility Guidelines 1.0". That single document has been divided into technology-specific documents that may evolve independently. Smaller technology-specific documents also allow authors to focus on a particular technology.

While the "Web Content Accessibility Guidelines 1.0" Recommendation [WCAG10] is a stable document, this series of companion documents is expected to evolve as technologies change and content developers discover more effective techniques for designing accessible Web sites and pages. In the near future, the Working Group intends to incorporate techniques for the Synchronized Multimedia Integration Language (SMIL) [SMIL] described in "Accessibility Features of SMIL" ([SMIL-ACCESS]) and techniques for Scalable Vector Graphics (SVG) [SVG] described in "Accessibility Features of SVG" ([SVG-ACCESS]). The Working Group also intends to incorporate techniques for non-W3C technologies such as ECMAScript, PDF and Flash.

The history of changes to the series of documents as well as the list of open and closed issues are available. Readers are encouraged to comment on the document and propose resolutions to current issues. Please send detailed comments on this document to the Working Group at w3c-wai-gl@w3.org; public archives are available.

The English version of this document is the only normative version. However, for translations in other languages see "http://www.w3.org/WAI/GL/WAI-WEBCONTENT-TRANSLATIONS".

The list of known errors in this document is available at "Errata in Web Content Accessibility Guidelines." Please report errors in this document to wai-wcag-editor@w3.org.

The Web Accessibility Initiative (WAI) of the World Wide Web Consortium (W3C) makes available a variety of resources on Web accessibility. WAI Accessibility Guidelines are produced as part of the WAI Technical Activity. The goals of the WCAG WG are described in the charter.

A list of current W3C Recommendations and other technical documents is available.

1 How this Document is Organized

Section 2 of this document reproduces the guidelines and checkpoints of the "Web Content Accessibility Guidelines 1.0" [WCAG10]. Each guideline includes:

• The guideline number.
• The statement of the guideline.
• A list of checkpoint definitions. Checkpoints are ordered according to their priority, e.g., Priority 1 before Priority 2.

Each checkpoint definition includes:

• The checkpoint number.
• The statement of the checkpoint.
• The priority of the checkpoint.
• A link back to the definition of the checkpoint in "Web Content Accessibility Guidelines 1.0" [WCAG10]. Definitions may also include informative notes, examples, cross references, and commentary to help readers understand the scope of the checkpoint.

Each checkpoint is followed by one or more links to techniques in the following documents:

• "Core Techniques for Web Content Accessibility Guidelines 1.0" ([WCAG10-CORE-TECHNIQUES]), which discusses the accessibility themes and general techniques that apply across technologies.
• "HTML Techniques for Web Content Accessibility Guidelines 1.0" ([WCAG10-HTML-TECHNIQUES]), which provides examples and strategies for authoring accessible Hypertext Markup Language (HTML) content.
• "CSS Techniques for Web Content Accessibility Guidelines 1.0" ([WCAG10-CSS-TECHNIQUES]), which provides examples and strategies to help authors write Cascading Style Sheets (CSS) as part of accessible content design.

1.1 Priorities

Each checkpoint has a priority level assigned by the Working Group based on the checkpoint's impact on accessibility.

[Priority 1]

A Web content developer must satisfy this checkpoint. Otherwise, one or more groups will find it impossible to access information in the document. Satisfying this checkpoint is a basic requirement for some groups to be able to use Web documents.

[Priority 2]

A Web content developer should satisfy this checkpoint. Otherwise, one or more groups will find it difficult to access information in the document. Satisfying this checkpoint will remove significant barriers to accessing Web documents.

[Priority 3]

A Web content developer may address this checkpoint. Otherwise, one or more groups will find it somewhat difficult to access information in the document. Satisfying this checkpoint will improve access to Web documents.

Some checkpoints specify a priority level that may change under certain (indicated) conditions.

2 Techniques for Web Content Accessibility Guidelines

Checkpoints:

1.1 Provide a text equivalent for every non-text element (e.g., via "alt", "longdesc", or in element content). This includes: images, graphical representations of text (including symbols), image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ASCII art, frames, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video. [Priority 1] (Checkpoint 1.1)

• Core Techniques: Text equivalents
• HTML Techniques: Images used as bullets
• HTML Techniques: Text for images used as links
• HTML Techniques: Short text equivalents for images ("alt-text")
• HTML Techniques: Long descriptions of images
• HTML Techniques: Text equivalents for client-side image maps
• HTML Techniques: Text and non-text equivalents for applets and programmatic objects
• HTML Techniques: Text equivalents for multimedia
• HTML Techniques: Describing frame relationships
• HTML Techniques: Writing for browsers that do not support FRAME
• HTML Techniques: Graphical buttons
• HTML Techniques: Alternative presentation of scripts

1.2 Provide redundant text links for each active region of a server-side image map. [Priority 1] (Checkpoint 1.2)

Refer also to checkpoint 1.5 and checkpoint 9.1.

• Core Techniques: Text equivalents
• HTML Techniques: Server-side image maps

1.3 Until user agents can automatically read aloud the text equivalent of a visual track, provide an auditory description of the important information of the visual track of a multimedia presentation. [Priority 1] (Checkpoint 1.3)

• Core Techniques: Visual information and motion

1.4 For any time-based multimedia presentation (e.g., a movie or animation), synchronize equivalent alternatives (e.g., captions or auditory descriptions of the visual track) with the presentation. [Priority 1] (Checkpoint 1.4)

• Core Techniques: Audio information
• HTML Techniques: Directly accessible applets

1.5 Until user agents render text equivalents for client-side image map links, provide redundant text links for each active region of a client-side image map. [Priority 3] (Checkpoint 1.5)

Refer also to checkpoint 1.2 and checkpoint 9.1.

• Core Techniques: Text equivalents
• HTML Techniques: Redundant text links for client-side image maps

Checkpoints:

2.1 Ensure that all information conveyed with color is also available without color, for example from context or markup. [Priority 1] (Checkpoint 2.1)

• Core Techniques: Structure vs. Presentation
• CSS Techniques: Ensuring information is not in color alone

2.2 Ensure that foreground and background color combinations provide sufficient contrast when viewed by someone having color deficits or when viewed on a black and white screen. [Priority 2 for images, Priority 3 for text]. (Checkpoint 2.2)

• HTML Techniques: Color in images
• CSS Techniques: Color Contrast

Checkpoints:

3.1 When an appropriate markup language exists, use markup rather than images to convey information. [Priority 2] (Checkpoint 3.1)

• Core Techniques: Structure vs. Presentation
• HTML Techniques: Markup and style sheets rather than images: The example of math
• CSS Techniques: Generated content

3.2 Create documents that validate to published formal grammars. [Priority 2] (Checkpoint 3.2)

• HTML Techniques: The !DOCTYPE statement

3.3 Use style sheets to control layout and presentation. [Priority 2] (Checkpoint 3.3)

• Core Techniques: Structure vs. Presentation
• HTML Techniques: Emphasis
• CSS Techniques: Text instead of images
• CSS Techniques: Text formatting and position
• CSS Techniques: Layout, positioning, layering, and alignment

3.4 Use relative rather than absolute units in markup language attribute values and style sheet property values. [Priority 2] (Checkpoint 3.4)

• HTML Techniques: Directly accessible applets
• HTML Techniques: Sizing frames with relative units
• CSS Techniques: Units of measure

3.5 Use header elements to convey document structure and use them according to specification. [Priority 2] (Checkpoint 3.5)

• Core Techniques: Structure vs. Presentation
• HTML Techniques: Section headings

3.6 Mark up lists and list items properly. [Priority 2] (Checkpoint 3.6)

• Core Techniques: Structure vs. Presentation
• HTML Techniques: Lists
• CSS Techniques: Providing contextual clues in HTML lists

3.7 Mark up quotations. Do not use quotation markup for formatting effects such as indentation. [Priority 2] (Checkpoint 3.7)

• HTML Techniques: Quotations

Checkpoints:

4.1 Clearly identify changes in the natural language of a document's text and any text equivalents (e.g., captions). [Priority 1] (Checkpoint 4.1)

• HTML Techniques: Identifying changes in language

4.2 Specify the expansion of each abbreviation or acronym in a document where it first occurs. [Priority 3] (Checkpoint 4.2)

• HTML Techniques: Acronyms and abbreviations

4.3 Identify the primary natural language of a document. [Priority 3] (Checkpoint 4.3)

• HTML Techniques: Identifying the primary language

Checkpoints:

5.1 For data tables, identify row and column headers. [Priority 1] (Checkpoint 5.1)

• HTML Techniques: Identifying rows and column information

5.2 For data tables that have two or more logical levels of row or column headers, use markup to associate data cells and header cells. [Priority 1] (Checkpoint 5.2)

• HTML Techniques: Identifying rows and column information

5.3 Do not use tables for layout unless the table makes sense when linearized. Otherwise, if the table does not make sense, provide an alternative equivalent (which may be a linearized version). [Priority 2] (Checkpoint 5.3)

• Core Techniques: Structure vs. Presentation
• HTML Techniques: Tables for layout
• CSS Techniques: Layout, positioning, layering, and alignment

5.4 If a table is used for layout, do not use any structural markup for the purpose of visual formatting. [Priority 2] (Checkpoint 5.4)

• Core Techniques: Structure vs. Presentation
• HTML Techniques: Tables for layout

5.5 Provide summaries for tables. [Priority 3] (Checkpoint 5.5)

• HTML Techniques: Providing summary information

5.6 Provide abbreviations for header labels. [Priority 3] (Checkpoint 5.6)

• HTML Techniques: Providing summary information

Refer also to checkpoint 10.3.

Checkpoints:

6.1 Organize documents so they may be read without style sheets. For example, when an HTML document is rendered without associated style sheets, it must still be possible to read the document. [Priority 1] (