Web Content Accessibility Guidelines 2.0

Introduction

Purpose

This document outlines design principles for creating accessible Web content. When these principles are ignored, individuals with disabilities may not be able to access the content at all, or they may be able to do so only with great difficulty. When these principles are employed, they also make Web content accessible to a variety of Web-enabled devices, such as phones, handheld devices, kiosks, network appliances, etc. By making content accessible to a variety of devices, that content will also be accessible to people in a variety of situations.

This document expands four principles of design into guidelines for creating accessible Web content. When these guidelines and underlying principles are ignored, individuals with disabilities may not be able to access the content at all, or they may be able to do so only with great difficulty. When they are employed, they also make Web content accessible to a variety of Web-enabled devices, such as phones, handheld devices, kiosks, network appliances, etc. By making content accessible to a variety of devices, that content will also be accessible to people in a variety of situations.

The design principles in this document represent broad concepts that apply to all Web-based content. They are not specific to HTML, XML, or any other technology. This approach was taken so that the design principles could be applied to a variety of situations and technologies, including those that do not yet exist.

How to read this document

In order to facilitate understanding of the guidelines and to help people focus in on just the parts they need, the guidelines are presented as a set of interrelated documents. There are basically 3 layers to the guidelines information.

This document is the first of three layers that become increasingly specific about the technology that creates Web content. Checklists and techniques are the second and third layers, respectively. People can focus on what they need through separating conceptual guidelines from checklists of specific technologies from techniques for those technologies.

1 - Top layer First Layer—Overview of Design Principles, Guidelines, Checkpoints

The ~~top~~ first layer, is titled "Web Content Accessibility Guidelines 2.0"~~. It is the document you are currently reading. This document~~ provides:

An introduction
The 4 major Guidelines for accessibility (Perceivable, Operable, Understandable and Robust).
The (non-technology-specific) checkpoints for each guideline (18 in total).
Success criteria (normative), and definitions, benefits and examples (all non-normative) for each checkpoint
An appendix containing definitions, references and other support information.

2 - Second Layer—Technology-specific Checklists

In addition to the general guidelines, there will be a series of technology-specific checklist documents. These documents will provide information on what is required when using different technologies in order to meet the WCAG 2.0 Working Draft access guidelines.

Editorial Note: These checklists do not yet exist. At the present time, the checklists are expected to be non-normative, though no formal decision has been made.

3 - Bottom layer - Technology-specific application information Third Layer—Techniques

The techniques documents will include code examples, screen shots, and other information specific to a technology. These documents will be non-normative. They will contain different strategies for meeting the requirements, as well as the current preferred approaches current preferred approaches—it is not clear whether current modifies preferred or approaches; if it modifies approaches, a comma needs to separate the co-equal modifiers of approaches; if it modifies preferred, a comma is not needed, but you should drop current. If you leave it without a comma, one might infer that non-current approaches are a possiblity that WAI rejects out of hand. After all, you are choosing the current over the non current. A question begins to be begged. What about non-current preferred approaches. If the sense is that the techniques documents will be kept current, simply say that in a declarative sentence. where they exist. Examples include:

Hypertext Markup Language (HTML) and Extensible Hypertext Markup Language (XHTML) Techniques
Cascading Style Sheets (CSS) Techniques
Server-side Scripting Techniques
Client-side Scripting Techniques
Scalable Vector Graphics (SVG) Techniques
Synchronized Multimedia Integration Language (SMIL) Techniques
Extensible Markup Language (XML) Techniques

(These will become active links as the corresponding working drafts are published)

Audience

These guidelines have been written to meet the needs of many different audiences from policy makers, to managers, to those who create Web content, to those who code the pages. Every attempt has been made to make the document as readable and usable as possible, while still retaining the accuracy and clarity needed in a technical specification. For first time users, the work of the Education and Outreach Working Group of the Web Accessibility Initiative is highly recommended.

Scope

These guidelines cover a wide range of issues and recommendations for making Web content more accessible. They include recommendations to make pages accessible and usable by people with a full range of disabilities. In general, the guidelines do not include standard usability recommendations, except where they have specific ramifications for accessibility beyond standard usability impacts.

Priorities and Techniques

This WCAG 2.0 Working Draft does not assign priorities to checkpoints, as did WCAG 1.0. Instead, there are two types of checkpoints; CORE and EXTENDED.

The main WCAG 2.0 Working Draft document does not include technology-specific implementation requirements or techniques, but it does include links to technology-specific requirements (checklists) as well as technology-specific examples ~~and~~ (techniques).

This Working Draft of WCAG 2.0 is a follow-on and evolution of WCAG 1.0 and reflects feedback received since the publication of WCAG 1.0 in May 1999. Although the same approaches to accessibility are followed in 1.0 and 2.0, the organization and structure have been improved significantly. In addition, the principles have been worded to make it easier to understand their application across the wide range of existing and emerging technologies.

The Web Content Accessibility Guidelines Working Group is working carefully to enable organizations and individuals that are currently using WCAG 1.0 (which remains stable and referenceable at this time) to ensure that they will eventually be able to make a smooth transition to WCAG 2.0. To understand how this eventual transition would be facilitated, please refer to the (draft) Checkpoint Mapping Between WCAG 1.0 and the WCAG 2.0 Working Draft for more detail on current correspondences.

Conformance

Editorial Note: As we publish this Working Draft of WCAG 2.0, the WCAG WG is in the midst of significantly changing the conformance scheme from previous drafts. This section outlines the conformance structure used throughout this document. Feedback, comments, and proposals are encouraged.

Checkpoints are divided into two groups:

Core Checkpoints: To conform to WCAG 2.0, the Required Success Criteria of Core Checkpoints must be satisfied. Best Practice items do not need to be met to claim conformance to a Core Checkpoint.
Extended Checkpoints: These are additional checkpoints that may be reported in addition to Core conformance if the Required Success Criteria for a given Extended Checkpoint are satisfied. Best Practice items to do not need to be met to claim conformance to an Extended Checkpoint.

Conformance Claims

In order to make a valid conformance claim for a Web resource, the resource must satisfy all required success criteria for all Core checkpoints.
A conformance claim of "WCAG 2.0 Core" can be made if all required success criteria for all core checkpoints have been met.
A conformance claim of "WCAG 2.0 Extended" can be made if all required success criteria for all core checkpoints and all extended checkpoints have been met.
A conformance claim of "WCAG 2.0 Core+" can be made if all required success criteria for all core checkpoints and some extended checkpoints have been met.

Editorial Note: Feedback from WCAG 1.0 indicates that developers often do not attempt to meet any Priority 2 Checkpoints because there is no way to indicate in the conformance claim that they have "done more than Level A but not enough to claim Level AA." "Core+" is a proposal that allows developers to say, "I do more than Core but not all of the Extended." However, the WCAG WG has several issues and questions about Core+ conformance claims:
- How should conformance claims state which Extended Checkpoints are met? in metadata? in a site accessibility statement? some other method?
- How should conformance claims state how many Extended Checkpoints are met? in metadata? with core+n (n=number of Extended checkpoints)? in a site accessibility statement? some other method?
- If Core+ is claimed, should we require a statement about which Extended checkpoints are met?
- Is there a separate logo for each level: core, core+, and extended? If so,what does the logo point to?
- Comparisons of Core+ conformance claims ~~can not~~ cannot be made unless detailed information is provided about the Extended checkpoints that are met.
- Should detailed conformance information be provided in metadata? There is doubt that it will be kept up to date, especially if the site becomes less accessible over time. Also, we may be unable to require metadata since some companies have indicated that the legal and ISO 9000 ramifications would prevent them from posting metadata describing the exact conformance.
- If it were possible to claim "Core+n" where "n" denotes the number of Extended Checkpoints that are met, some developers report that they would be encouraged to meet more Extended Checkpoints and increase the number they can report. However, people are likely to compare the number and these comparisons could be misleading. For example, a site that claims "Core+2" could be more accessible than a site that claims "Core+3" depending on which checkpoints are met.

A new concept to me, since the site I manage makes no claims. It is accessible to assistive technology in every aspect I know or is brought to my attention.

My thought, however, is that the gray area between core and extended should be explained by the site sponsor in a statement linked from some W3C-approved icon on the site, such as on the footer on the site home page, that ennumerates the extended checkpoints that the site fails to meet, and why the sponsor has decided to forego meeting those checkpoints.

All conformance claims must include (at minimum):

The version of the guidelines to which a conformance claim is made and the dated URI of the guidelines document.
The scope of the conformance claim. The scope describes which parts of a site or application are included in the claim.

Editorial Note: Should exclusions be allowed for certain types of content, such as third-party or copyrighted material that is being reprinted? Yes. How does one define scope? Is it an end-to-end process that the user should be able to complete? Is it a path through accessible content? Since a site is like a web, a single path does not exist, nor is there a single end-to-end process. There is a bit of the Core+ question here. The scope should state the site is subject to the claim of conformance in its entirety, if that is so. When a site is not entirely subject to the claim, the scope should explain those portions or functions not conforming and the reasons the site sponsor has elected to exclude the non-conforming portions or functions.
The set of checkpoints being claimed (Core or Extended).
The date the conformance claim was made.

Sites that conform to WCAG 1.0

Sites that currently conform to WCAG 1.0 that want to shift towards WCAG 2.0 will want to capitalize on past accessibility efforts. A qualified conformance statement could allow them this flexibility. For example, a conformance claim might include the following statement, "Materials created or modified before 24 April 2003 conform to WCAG 1.0. Materials created or modified on or after 24 April 2003 conform to WCAG 2.0."

Editorial Note: In some instances, the WCAG 2.0 Working Draft may be easier to conform to than the WCAG 1.0 Recommendation while other criteria might be harder to meet in WCAG 2.0 than in WCAG 1.0. The WCAG WG will consider the differences between WCAG 1.0 and WCAG 2.0 conformance and offer advice to developers who currently conform to WCAG 1.0. This advice might take the form of a WCAG 1.0 conformance profile to WCAG 2.0 and information about migrating from WCAG 1.0 to WCAG 2.0. This advice is not yet available.

Overview of Design Principles

~~The overall goal is to create~~ Accessible Web content ~~that~~ is perceivable, operable and understandable by the broadest possible range of users and compatible with their wide range of assistive technologies, now and in the future. ~~The basic~~ Four guidelines expand these principles ~~are expressed in the 4 guidelines~~:

Perceivable. Ensure that all content can be presented in form(s) that can be perceived by any user - except those aspects of the content that cannot be expressed in words.
Operable. Ensure that the interface elements in the content are operable by any user.
Understandable. Make ~~it as easy as possible to understand the~~ content and controls understandable. Tom Note: The statement here and the wording of Guideline 3 should conform; the inclusion of "as many as possible" is too soft. If absolutely necessary, add "to users" at the end of the rewritten text.
Robust. Use Web technologies that maximize the ability of the content to work with current and future accessibility technologies and user agents.

Accessible Web content benefits a variety of people, not just people with disabilities. In the physical world, ramps are used by bicycles, people pushing strollers, and people in wheelchairs. Similarly, accessible Web content is beneficial to a variety of people with and without disabilities. For example, people who are temporarily operating under constrained conditions like operating in a noisy environment where they ~~can not~~ cannot hear well at all, or driving their car where their eyes are busy would benefit from an accessible site. Likewise, a search engine can find a famous quote in a movie if the movie is captioned.

Note:

These principles apply only to Web content presented to a human reader. A structured database or metadata collection where the data is intended for use by another machine, and that requires no interface, lies outside the scope of these guidelines.

User needs

Here are a few scenarios, by no means an exhaustive list, of the variations and types of disabilities and needs:

Someone who cannot hear will want to see the information normally presented via sound.
Someone who cannot see will want to hear, or read through braille, information that is usually presented visually.
Someone who does not have the strength to move quickly or easily will want to use as little movement as possible and have as much time as ~~they need~~ necessary, when operating Web interfaces."Someone" and "they" do not match in number.
Someone who does not read well may want to hear the information read aloud.

If Web content ~~employs~~ uses the design principles described in this document, then users should be able to access the content using adaptive strategies and assistive technologies. A screen reader is an example of an assistive technology that reads the page aloud. There are many other tools people with disabilities employ to make use of Web content. For more in-depth scenarios of people with disabilities using accessible and inaccessible Web content, please read "How People with Disabilities Use the Web".

Designing Accessible Web Content

These guidelines provide the basic requirements for designing accessible Web content. This document is not designed to provide the background needed to learn about accessible Web design in a thorough or effective manner for those interested in learning. Readers are therefore referred to the Education and Outreach Working Group of the Web Accessibility Initiative.

Guideline 1: PERCEIVABLE. Make Content Perceivable by Any User

Core Checkpoints for Guideline 1

1.1 [CORE] All non-text content that can be expressed in words has a text equivalent of the function or information that the non-text content was intended to convey. [was 1.1]

Required Success Criteria for Checkpoint 1.1

The items in these numbered lists are sentences. They should be in sentence case, beginning with a capital letter. I will change the case in this list, but not in all lists.

nNon-text content that can be expressed in words has a text-equivalent explicitly associated with it.
nNon-text content that ~~can not~~ cannot be expressed in words has a descriptive label provided as its text-equivalent.
- The text equivalent should fulfill the same function as the author intended for the non-text content (i.e. it presents all of the intended information and/or achieves the same function of the non-text content). Tom note: Does this unordered, single item list pertain solely to item two in the numbered list? Visually, since it is indented beneath item two, I take it to apply only to item two. Logically, it appears to apply both item one and item two, however.

Best Practice for Checkpoint 1.1

Until there is more that one item, remove the ol construct.

non-text content that ~~can not~~ cannot be expressed in words has a text equivalent for all aspects that can be expressed in words.

Definitions for Checkpoint 1.1 (Informative)

text equivalent

A text equivalent

serves the same function as that the non-text content was intended to serve;
communicates the same information as the non-text content was intended to convey;
or ~~may contain~~ contains structured content or metadata.

Note:

Text-equivalents should be easily convertible to braille or speech, displayed in a larger font or different colors, fed to language translators or abstracting software, etc.

non-text content

non-text content includes but is not limited to images, text in raster images, image map regions, animations (e.g., animated GIFs), ASCII art, 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. Scripts, applets, and programmatic objects are not covered in this definition and are addressed in checkpoint 4.3.

Benefits of Checkpoint 1.1 (Informative)

Individuals who are blind, have low vision, have cognitive disabilities or have trouble reading text for any reason can have the text read aloud to them.
Individuals who are deaf, are hard of hearing or who are having trouble understanding the audio information for any reason can read the text presentation or have it translated and presented as sign language by their assistive technology.
Individuals who are blind or deaf-blind can have the information presented in braille.

Examples of Checkpoint 1.1 (Informative)

Example 1: an image used as a button. (short description of function)

A right arrow icon is used to link to the next slide in a slide show. The text equivalent is "Next Slide," so that what is read by a screen reader would be "link: Next Slide."
Example 2: a data chart. (short label + longer description)

A bar chart compares how many widgets were sold in June, July, and August. The short label says, "Figure one - Sales in June, July and August." The longer description identifies the type of chart or graph, provides a high-level summary of the data comparable to that available from the chart or graph, and lists the data themselves.
Example 3: an animation. (short label + longer description)

An animation shows how to tie a knot. The short label says, "An animation showing how to tie a square knot." The longer explanation describes the hand movements needed to tie the knot.
Example 4: an audio file of a speech. (short label + transcript)

An audio file is embedded in a Web page. The short label says, "Chairman's speech to the assembly." A text link, "transcription of speech," ~~to a text transcript~~ is provided immediately after the ~~clip~~ short label.
Example 5: an audio file of a symphony. (short label)

An audio file is embedded in a Web page. The short label says, "Beethoven's 5th Symphony performed by the Vienna Philharmonic Orchestra."

1.2 [CORE] Synchronized media equivalents are provided for time-dependent presentations. [was 1.2]

Editorial Note (06/10/03): There is discussion about moving some of the current success criteria from Required to Best Practice or to an Extended checkpoint. The issue stems from trying to apply the success criteria to every Web cam, newscast, and home broadcast. Another approach is to allow a conformance claim to state, for example, "All pages and applications on this site meet the Core checkpoints of WCAG 2.0 except the Web cam at http://example.org/webcam/."

Required Success Criteria for Checkpoint 1.2

an audio description is provided of for all significant visual information in scenes, actions, and events that cannot be perceived from the sound track alone ~~to the extent possible given~~ within the constraints posed by the existing audio track ~~and limitations on~~ or by freezing the ~~audio visual~~ program to insert additional auditory description.

Note:

When adding audio description to existing materials, the amount of information conveyed through audio description is constrained by the amount of space available in the existing audio track unless the audio/video program is periodically frozen to insert audio description. However, it is often impossible or inappropriate to freeze the audio/visual program to insert additional audio description.
all significant dialogue and sounds are captioned, barring

~~Exception:~~

~~If the~~ Web content that is real-time, ~~and~~ audio-only, ~~and~~ not time-sensitive and not interactive, in which case a transcript or other non-audio equivalent is sufficient.
descriptions and captions are synchronized with the events they represent.
if the Web content is real-time video with audio, real-time captions are provided unless the content:
- is a music program that is primarily non-vocal This unordered list is unnecessary; the conditional sentence stands on its own.
~~if the~~ Web content that is real-time, non-interactive video (e.g., a Webcam of ambient conditions), ~~either provide~~ has an equivalent that conforms to checkpoint 1.1 (e.g., ~~an ongoing~~ a periodically refreshed update of weather conditions is provided), or a link to an equivalent that conforms to checkpoint 1.1 (e.g., a link to a weather Web site).
if When a pure audio or pure video presentation requires a user to respond interactively at specific times in the presentation, ~~then~~ a time-synchronized equivalent (audio, visual or text) presentation is provided.

Exception:

If content is rebroadcast from another medium or resource that complies to broadcast requirements for accessibility (independent of these guidelines), the rebroadcast satisfies the checkpoint if it complies with ~~the other~~ those independent guidelines.

Best Practices for Checkpoint 1.2

a text document is provided that merges all audio and video descriptions and captions into a collated script ~~(that provides dialog, important sounds and important visual information in a single text document) is provided~~.
captions and audio descriptions are provided for all live broadcasts which provide the same information.
the presentation does not require the user to read captions and the visual presentation simultaneously in order to understand the content.

Definitions for Checkpoint 1.2 (Informative)

time-dependent presentation

A time-dependent presentation is a presentation that

is composed of synchronized audio and visual tracks (e.g., a movie), OR
requires the user to respond interactively at specific times in the presentation.

media equivalents

Media equivalents present essential audio information visually (captions) and essential video information auditorily (audio descriptions).

[Definition: captions are text equivalents of auditory information from speech, sound effects, and ambient sounds that are synchronized with the multimedia presentation.]
[Definition: audio descriptions are equivalents of visual information from actions, body language, graphics, and scene changes that are voiced (either by a human or a speech synthesizer) and synchronized with the multimedia presentation.]

Benefits of Checkpoint 1.2 (Informative)

People who are deaf or have a hearing loss can access the auditory information through the captions.
People who are blind or have low vision, as well as those with ~~cognitive~~ disabilities ~~who have~~ that make it difficulty to interpret~~ing visually~~ what is happening visually, benefit from the audio descriptions of the visual information. Tom note: I imagine I am over-reacting, but among blind and visually handicapped persons are some who might take offense at being "lumped" with persons with cognitive disabilites. Hence, this modification to make less specific the cause of the disability.

People without disabilities also benefit from the media equivalents.

People in noisy environments or with muted sound often use captions.
Captions are used by many to develop language and reading skills.
Audio descriptions also provide equivalent visual information for people who are temporarily looking away from the video presentation, such as when following an instructional video and looking at their hands.
Captions and text descriptions can also be used to index and search media files.

Note:

Time-dependent presentations requiring people to use a single sense to follow two or more things at the same time may present significant barriers to some users. Depending on the nature of the presentation, it may be possible to avoid scenarios where, for example, a deaf user would be required to watch an action on the screen and read the captions at the same time. However, this may not be available for live broadcasts (e.g. a football game). Where possible (especially for education and training materials), provide content so that it does not require tracking multiple simultaneous events with the same sense~~, or,~~ . Alternatively, give the user the ability to freeze the video, so that captions can be read without missing the video.

Examples of Checkpoint 1.2 (Informative)

Example 1: a movie clip with audio description and captions.

A clip from a movie is published on a Web site. In the clip, a child is trying to lure a puppy to the child's bedroom by laying a trail of crumbs. The child mumbles inaudibly to himself as he lays the trail. When not watching the video, it is not obvious that he is laying a trail of crumbs since all you hear is the mumbling. The audio description that is interspersed with the child's mumbling says "Charlie lays a crumb on each stair leading to his room." The caption that appears as he mumbles is, "[inaudible mumbling]."
Example 2: a video clip of a news story.

A video clip accompanies a news story about the recent flooding in a major city. In voice-over, the reporter describes what is seen~~, for everyone~~. No audio description is necessary. ~~The c~~Captions display ~~what~~ the reporter's words ~~is saying~~.
Example 3: a silent animation.

An animation shows a pantomime climbing a ladder. There is no audio track for this animation. No captions or audio description are required. Instead, a text equivalent is provided as described in checkpoint 1.1.

1.3 [CORE] Both [information/substance] and structure are separable from presentation. [was 1.3]

An apparent division of opinion, information vs. substance. In its most elemental sense, content that enters the conscience of a user does so because that content has touches the user in a cognitive sense. Prospero would tell us it is "such stuff as dreams are made on" (Tempest, IV:1). There is more of the ethereal in "information" than in "substance". The latter, though its first meaning is essential nature, carries with it the notion of something physical. Since the content of a object on the Web is inherently not physical, I would argue to use information. An alternative might be meaning, although structure of information is also a source of meaning. There you have it, an excursion toward epistomology.

Required Success Criteria for Checkpoint 1.3

the following can be derived programmatically (i.e., through a markup or data model that ~~is assistive technology compatible~~ conforms to universal standards) from the content without requiring interpretation of presentation. I suggest killing compatible with assistive technology, because it is my understanding that content and the user agents making use of that content are most compatible when both are using universal standards, such as W3C TRs, although I admit that W3C TRs are not standards in the strict sense.
1. any hierarchical elements and relationships, such as headings, paragraphs and lists
2. any non-hierarchical relationships between elements such as cross-references and linkages, associations between labels and controls, associations between cells and their headers, etc.
3. any emphasis

Since the nested list is ordered, the notion of sequence or hierarchy obtains. Why not change it to an unordered list? Also, I should note that the statement under 1 is the only success criteria. It does not need to be numbered. As well, the three list items are not sentences, so they correctly begin with lower case and end without punctuation.

Definitions for Checkpoint 1.3 (Informative)

I note that in this definition list, as in ordered and unordered lists, the block element for a paragraph is nested inside the block elements for definition data or list item. I suspect this is so that there will be leading (that printer's term for blank space) between the block elements. Since the document conforms to XHTML, I would encourage dropping the paragraph container to achieve leading and using a CSS declaration to insert margins.

Also, you could drop the repeated word at the beginning of each definition. It is unnecessary.

content: Content is the information or meaning and function. Without commas, trouble follows. Do we parse this as content is either the information or meaning and function, or do we parse it as content is the information (or, as an alternative, the meaning) and function. My hunch is that function is meant to partner with information and not be an alternative, or part of an alternative, to information. If meaning is, in fact, supplied as an alternative to the word information, the document would be stronger if you drop the alternative and stick, with bold assurance, to a single word for the concept—information.
presentation: Presentation is the rendering of the content and structure in a form that can be sensed by the user.
structure: Structure includes both hierarchical structure of the content and non-hierarchical relationships such as cross-references, or the correspondence between header and data cells in a table.

Benefits of Checkpoint 1.3 (Informative)

Separating content and structure from presentation allows Web pages to be presented differently to meet the needs and constraints of different users without losing any of the information or structure. For example, information that was originally intended to be presented visually can be presented ~~via speech or braille (text) that was originally intended to be presented visually~~ auditorily (screen-reader) or tactilely (refreshable braille display).

Examples of Checkpoint 1.3 (Informative)

Example 1: a multi-column document.

A document is marked up with headings, paragraphs and other structural features. It is presented visually in three columns. The markup that creates the columns is separate from the markup that specifies the logical structure of the document.
Example 2: a scrolling list of stock prices.

Current stock quotes are scrolled horizontally across the screen. The data are separate from the methods used to scroll the text across the page.
Example 3: a 3-dimensional site map.

A custom user interface renders 3D visualizations, from a data source, of the pages on a site and how they relate to one another ~~from a data source~~. Any hierarchical relationships, groupings, cross-references, etc. would originate in the data source so that the structure of the site ~~alternate interfaces~~ could be rendered ~~(from the same source) that expose the structure of the site~~ in an accessible form using an alternate interface. (See also checkpoint 4.3)
Example 4: a list that allows users to sort information on a page according to preference.

A script allows a user to rearrange a categorical listing of music files by date, artist, genre, or file size. The script updates both the structure and the presentation ~~accordingly~~ when generating alternate views.

1.4 [CORE] All characters and words in the content can be unambiguously decoded. [was 1.6]

Required Success Criteria for Checkpoint 1.4

Drop the ordered list when only one item long

text in the content is provided in Unicode, or sufficient information is provided so that it can be automatically mapped back to Unicode.

Best Practice for Checkpoint 1.4

abbreviations and acronyms are clearly identified each time they occur. (See also checkpoint 3.1)
symbols such as diacritic marks that are found in standard usage of the natural language of the content, and that are necessary for unambiguous identification of words, are present; or another standard mechanism for disambiguation is provided.

Benefits of Checkpoint 1.4 (Informative)

Facilitating unambiguous decoding of characters and words in content is also helpful for individuals who are learning to read or learning a second language.

Examples of Checkpoint 1.4 (Informative)

Example 2: an acronym in a page title.

In the following heading, "People of the W3C." the acronym "W3C" is marked as an acronym. Because it has been marked appropriately, the user agent would be able to speak the letters of the acronym one at a time rather than attempting to pronounce it as though it were a word.

Extended Checkpoints for Guideline 1

1.5 [EXTENDED] Structure has been made perceivable to more people through presentation(s), positioning, and labels. [was 1.4]

Kill "to more people". It does not add to the statement.

Required Success Criteria for Checkpoint 1.5

No ordered lists for one item.

the structural elements present have a different visual appearance or auditory characteristic from each other and from body text.

Best Practices for Checkpoint 1.5

the structural emphases are chosen to be distinct on different major visual display types (e.g. black and white, small display, mono audio playback).
content is constructed such that users can control the presentation of the structural elements.
alternate presentation formats are available to vary the emphasis of the structure.

Considerations

Editorial Note (22 May 2003): The items listed below were categorized as "additional items" in the April 29 draft. Should these be moved to techniques?

Techniques would be an appropriate place.

I would argue that documents use correct structural markup appropriate to the meaning of the content and leave to the user and functionality of the user's agent auditory distinctions "for major headings, sections and other structural elements."

Number 5, table of contents, should specify a hyperlinked TOC. It is not clear to me why number five falls into this list. I guess it is because, when one uses correct and appropriate structural markup, content is contained in an outline hierarchy. That outline is an appropriate table of contents and its presentation calls out for hyperlinks. I guess the technique document will make that clear.

for visual presentations, use font variations, styles, size and white space to emphasize structure.
use color and graphics to emphasize structure.
for auditory presentations, use different voice characteristics and/sounds for major headings, sections and other structural elements.
if content is targeted for a specific user group and the presentation of the structured content is not salient enough to meet the needs of your audience, use additional graphics, colors, sounds, and other aspects of presentation to emphasize the structure.
provide a table of contents or navigation map of the document.

Benefits of Checkpoint 1.5 (Informative)

Presentation that emphasizes structure:

enables users ~~with cognitive and visual disabilities~~ to orient themselves within the content,
enables ~~all~~ users to move quickly through the content and notice major content divisions
enables ~~all~~ users~~, but particularly users with visual or cognitive disabilities~~ to focus on important content,
enables ~~all~~ users~~, but particularly users with visual or cognitive disabilities~~ to distinguish the different types of content.

Examples of Checkpoint 1.5 (Informative)

Example 1: documentation for a product.

Identifying chapters in the structure of a book is appropriate and accepted use of labeling the structure. Within the chapters, headings identify (label) changes in context and highlight ideas contained in the following text. Subtle differences between the appearance of the chapter title and the section headings helps the user understand the hierarchy and relationship between the title and headings. The only difference might be font size and margin indentation when presented visually, and spoken in a ~~difference~~ different voice or preceded by a sound when presented auditorily.
Example 2: a data table. Speaking from experience with data tables that correctly identify columns and rows, I do not believe this is optional. When correctly coded, a screen reader can empower a user to both navigate and to understand a data table.

Groups of rows or columns are labeled with headers.
Example 3: an audio presentation.

An audio rendering of a document, generated according to a style sheet, uses a different, more formal voice to read titles and headers so the listener can easily identify the words as a title and not part of the running text. I think it may be presumptuous to cause this to happen. Readers may find this annoying and prefer to use a function of their agent to toggle such auditory differences on and off.

1.6 [EXTENDED] Foreground content is easily differentiable from background for both auditory and visual default presentations. [was 1.5]

Required Success Criteria for Checkpoint 1.6

text content that is presented over a background image or pattern is implemented using mechanisms that allow the user to display the text without the background image or pattern.

Best Practice for Checkpoint 1.6

when text content is presented over a background image or pattern, the text is easily readable when the page is viewed in 256 grayscale.
text content is not presented over a background image or pattern; OR or the text is easily readable, when the page is viewed in black and white (no grayscale).
audio content does not contain background sounds, OR or the background sounds are at least 20 db lower than the foreground audio content.
text content is not presented over a background image or color, OR or the colors used for the text and background or background image pass the following test:
- no tests/algorithms are available at this time I find the test at this URL very useful, http://h10014.www1.hp.com/accessibility/color_contrast.htm. It is based on the statement of WAI (or is it vice versa) found at http://www.w3.org/TR/AERT#color-contrast.

Note:

A 20 db difference in sound level is roughly 4 times quieter (or louder).

Editorial Note: The working group is seeking an algorithm that measures contrast in a way that is accurate and testable enough that we could include it in the guidelines. One algorithm, which comes from the Techniques For Accessibility Evaluation And Repair Tools document, is currently under consideration for inclusion in the techniques, but the group has not yet found something that is specific enough to be included at the guidelines level.

Benefits of Checkpoint 1.6 (Informative)

Individuals with low vision can easily make out characters in the content, even if they don't have the wide field of view used by fully sighted persons to separate text from background images. Someone should check this wording. I am not sure that it is lack of "the wide field of view" that prevents persons with low vision distinguishing text when the contrast with the background is too small.
Individuals with hearing impairments that limit their ability to hear all of the frequencies of speech can ~~make out~~ distinguish the words ~~from~~ among the sounds they can hear, because they are not mixed with residual sounds from the music.

Examples of Checkpoint 1.6 (Informative)

Example 1: a background image on a page.

A background image and text are arranged so that there is no image behind the text, or the image is so faint that the difference between the darkest part of the image and the text (which is dark) meets the standard foreground/background contrast requirements. The image behind the text also does not contain lines that are about the same width as the characters, so they do not interfere with character recognition.
Example 2: speech over background sounds.

Because speech is often naturally mixed with background sounds (movies, live news etc) and cannot be easily removed or separated, captions are provided (under checkpoint 1.2) to make dialog understandable. However not all people can see or read the captions. Where speech is mixed or recorded so that it is at least 20 db above any background sounds, people do not need to rely on captions to understand the dialog.

Guideline 2: OPERABLE. Ensure that Interface Elements in the Content are Operable by Any User

There is a definite article in this statement where it appears under the four design principles. It seems to me that modifying elements with interface is sufficient. At any rate, the statement should be the same in both places.

Core Checkpoints for Guideline 2

2.1 [CORE] All functionality is operable at a minimum through a keyboard or a keyboard interface. [was 2.1]

Can "at a minimum" be dropped here? The phrase might have a home in the following explanation, but it does not appear necessary here.

Also, since require success criteria and best practice are single, the ordered list is unwarranted..

Required Success Criteria for Checkpoint 2.1

all of the functionality of the content, where the functionality or its outcome can be expressed concisely in words, is operable at a minimum through a keyboard or keyboard interface.

Note:

refer to checkpoint 4.3 for information regarding user agent support.

Best Practice for Checkpoint 2.1

wherever a choice between event handlers is available and supported, the more abstract event is used.

This best practice statement is difficult for me to understand, perhaps because I do not use event handlers. Nevertheless, the phrase, "available and supported" bothers me. What does available mean? What happens to this statement, if we drop "handlers"? Supported troubles me, because one cannot know with what agent a user may access a document. How about, "When multiple events can be chosen, the more abstract is used."?

Finally, for folks unversed in events and their handlers, where is the list of events ranked from concrete to abstract?

Why is there, following this note, an anchor with an id contained in an h5 element?

Definitions for Checkpoint 2.1 (Informative)

Editorial Note: [To Do] Add a definition of operable as meaning not using mouse keys or an infinite tabbing on a long doc or other unreasonably inefficient keyboard access. Add another definition that says something to the effect that access is efficient. That is, mouse keys can't be used as a way to provide access via keyboard and if a document has a very large number of links, some mechanism other than tabbing through them one at a time needs to be provided.

keyboard interface: A keyboard interface is the point where the application accepts any input that would come from the keyboard (or optional keyboard).
operable: Content that responds to user action is operable. [NOTE: The checkpoint makes it clear that the functionality of content needs to be available to keyboard access. I do not believe that "operable as meaning not using mouse keys . . ." can be correct. It is the manner of the user registering an action with the system that is in question, not the response of the system to user action.

Benefits of Checkpoint 2.1 (Informative)

Individuals who are blind (and cannot use pointing devices) can have access to the functionality of the Web content or site.
Individuals with severe physical disabilities can use speech input ~~(which~~ that simulates keystrokes) ~~to both~~ both to enter data and to operate the interface elements on the page.

Examples of Checkpoint 2.1 (Informative)

Example 1: operation with multiple input devices.

The content relies only on focus-in, focus-out, and activation events~~; these are~~ defined in the API of the environment for which the content is written.~~, and are~~ These events are ~~intended~~ able to be ~~operable~~ registered by a variety of input devices, including pointing devices, keyboards and speech input systems.
Example 2: examples of Web content that would, and would not, be operable from a keyboard or keyboard interface
- If it's written to be operable from a computer keyboard, it conforms. (because it is operable from the keyboard.)
- If it's written to be used on a device that doesn't usually have a keyboard such as a cell phone and but it can be controlled by an optional keyboard for that device, it conforms. (A person who needs a keyboard - or alternate keyboard - can use it to control the application.)
- If it's written to be used with a device that doesn't have a keyboard, but it could also be used by similar devices that do—and it would work with their keyboard—it conforms. (A person who needs a keyboard would not buy the device without the keyboard. That device may itself not be considered accessible. But the content can be controlled from a device with a keyboard and therefore conforms to this checkpoint.)
- If it's written to work with devices that do not have keyboards, and it ~~can not~~ cannot be used by any other devices that do have keyboards, then it does not conform. (It cannot be accessed via keyboard.)

2.2 [CORE] Users can control any time limits on their reading of , interaction with, or responses to appropriate content unless control is not possible due to nature of real time events or competition. [was 2.2]

Required Success Criteria for Checkpoint 2.2

An ordered list is not required for one item. In an unordered list of the sort we find here (lengthy individual items, or items demanding of internal punctuation), end each item with a semicolon and only include the conjunction at the beginning of the last item.

at least one of the following is true for each time limit:
- the user is allowed to deactivate the time limits;
- or the user is allowed to adjust the time limit over a wide range which is at least 10 times the average user's preference;
- or the user is warned before time expires and given at least 10 seconds to extend the time limit;
- or the time limit is due to a real-time event (e.g. auction), and no alternative to the time limit is possible;
- or the time limit is part of a competitive activity where timing is an essential part of the activity (e.g. competitive gaming or time-based testing).

Best Practice for Checkpoint 2.2

An ordered list is unnecessary with a single item.

wherever possible, activities are designed so that time limits are not an essential part of the activity. (e.g.; alternate forms of competition, testing, etc. are used that are not time based.).

Definitions for Checkpoint 2.2 (Informative)

appropriate content: Appropriate content is not subject to competitive length of time to respond and is not presented in real-time.
real-time events: Real-time events are ~~those that are based on the occurrence of events in real-time where the events~~ are not under the control of the author.
competitive activity: A competitive activity ~~is an activity where~~ uses timing is as an essential part of ~~the~~ its design ~~of the activity~~. Removal of the time element would change the performance of the participants. Versions of the activity (e.g. test) that have no time basis or time limits might be preferred and may be required for some venues but this would require a complete redesign of the activity (e.g. test) and may change the character and validation methodology and would therefore not fall under these guidelines.
: The struck text wanders from the definition. What you say is true, but it would be equally true, for example, that presenting tabluar data in a structure outside of data tables may change the character and validation methodology. Hence, such new content would not fall under these guidelines. The struck matter is a reply to an unspoken "what if?".
: If the struck matter must remain, remove "(e.g. test)", place a period after "venues", strike "but" and insert "Since,", strike the second "(e.g. test)", insert a comma after "methodology", strike "and" and insert "the new content", and strike "therefore".

Benefits of Checkpoint 2.2 (Informative)

People with reading disabilities, cognitive disabilities, and learning disabilities often need more time than most people to read and comprehend written text. People with physical disabilities might not be able to ~~move quickly or accurately enough to interact with moving objects~~ register their answer as quickly as they deduce the answer. I changed this because it is not only moving targets that can be a challenge.

Content that is updated often might not be processed and read in time or in the proper order by an assistive technology ~~or voice browser~~.

Examples of Checkpoint 2.2 (Informative)

Examples of content that requires a response within a timed interval:
- automatic refresh
- redirection
- blinking or scrolling text
- dialog that disappears after a short period
- shutdown or deactivation of page if activity is not received in a set amount of time
Example 1: blinking text.

Client-side scripting is used to create blinking text. The user can deactivate the use of scripting in his or her browser or override the use of scripts with a user style sheet.
Example 2: a news site that is updated regularly.

A news site causes its front page to be updated every 1/2 hour. The front page contains minimal text and primarily consists of links to content. A user who does not wish the page to update selects a checkbox. The checkbox is in the "user preferences" portion of the site which is one of the first links on each page. Stop Here

2.3 [CORE] User can avoid experiencing screen flicker. [was 2.3]

Editorial Note (06/10/03): This Checkpoint is currently included in the Core set of Checkpoints because the WCAG WG expects that it will be possible to test content for flicker and the result will be a flicker rate in Hz that can be stored in a machine-readable format. The WG also expects that a user could, in the future, be able to configure a client to only render content that flickers at "a rate greater than X" by which the client could compare the content metadata and the user's preference. If the assumption regarding a testing tool does not hold at time of final review of these guidelines, this checkpoint will be moved to the Extended set of Checkpoints."

Required Success Criteria for Checkpoint 2.3

At least one of the following is true:
1. content was not designed to flicker (or flash) in the range of 3 to 49 Hz.
2. if flicker is unavoidable, the user is warned of the flicker before they go to the page, and as close a version of the content as is possible without flicker is provided.
Editorial Note: We would like to include a third criteria here that would state that a test that was conducted and the pages passed. No test or tool exists yet though. We're looking into how such a test and/or tool might be designed.

Best Practice for Checkpoint 2.3

animation or other content does not visibly or purposely flicker between 3 and 49 Hz.
content that might create a problem has been tested [using XYZ tool]; only pages with unavoidable flicker remain and appropriate warnings along with a close alternative presentation have been provided for these pages.
(tougher test - that would make pages pass with even slower equipment. Hardware might be old or just slow for other reasons.)

Benefits of Checkpoint 2.3 (Informative)

Individuals with photosensitive epilepsy can have seizures triggered by flickering or flashing in the 3 to 49 flashes per second (Hertz) range with a peak sensitivity at 20 flashes per second.
Individuals with distractibility problems may not be able to focus on page content with flicker occurring in the same visual field.

Extended Checkpoints for Guideline 2

2.4 [EXTENDED] Structure and/or alternate navigation mechanisms have been added to facilitate orientation and movement in content. [was 3.1 and 3.2]

Required Success Criteria for Checkpoint 2.4

In documents greater than 50,000 words or sites larger than 50 perceived pages, the following are provided.
1. hierarchical structure mark up
2. Table of contents (or site map)
3. Alternate display orders (or alternate site navigation mechanisms)

Best Practice for Checkpoint 2.4

the content has been reviewed, taking into account the following strategies for facilitating orientation and movement, applying them as appropriate.
1. breaking up text into logical paragraphs
2. providing hierarchical sections and titles, particularly for longer documents
3. revealing important non-hierarchical relationships, such as cross-references, or the correspondence between header and data cells in a table, so that they are represented unambiguously in the markup or data model
4. dividing very large works into sections and or chapters with logical labels
5. others?

Editorial Note: One of the reasons for combining these two (old 3.1 and 3.2) is that they both get at the same basic issue. Also, on many sites, it is becoming increasingly difficult to tell when you are navigating within a site and when you are navigating within a document. This will only increase over time. Since the title of this thing is Web content, it is recommended that these two items be combined so that we are talking about Web content versus separating content from sites.

Definitions for Checkpoint 2.4 (Informative)

structure

The structure of content represents changes in context. For example,

A book is divided into chapters, paragraphs, lists, etc. Chapter titles help the reader anticipate the meaning of the following paragraphs. Lists clearly indicate separate, yet related ideas. All of these divisions help the reader anticipate changes in context.
A bicycle is divided into wheels and a frame. Further, a wheel is divided into a tire and a rim. In an image of the bicycle, one group of circles and lines becomes "wheel" while another group becomes "frame."

site navigation mechanism

A site navigation mechanism is a mechanism for easily orienting and moving about within the site. Site navigation mechanisms include but are not limited to:

A home page with hyperlinks on it and subsequent pages that link to the other pages at the site
site map(s)
search engine(s)
expanding outline(s)
dynamic fisheye views showing all linked pages or topics related to any page.
3-D virtual representations of site content

Benefits of Checkpoint 2.4 (Informative)

When the logical structure is provided in markup or a data model,
- Users with physical disabilities can use structure to more easily jump between paragraphs, chapters, sections etc.
- Users with cognitive disabilities can use structure (chapter titles, headers, etc.) to provide more context for the text that follows them. They also provide warning of a change in context and reorient the user to the new focus.
- Users with blindness or low vision can jump from header to header to get an overview or to more quickly "skim" to the section they are interested in.
- Readers with low vision can sometimes (depending on display technology) change how chapter titles and headers are displayed to make them more visible -and easier to use when skimming the document.
- the content can be presented on a variety of devices because the device software can choose only those elements of the content that it is able to display and display them in the most effective way for that device.
Providing different navigation mechanisms can provide a better match between different people's skills, background knowledge, visual vs. text orientation, and the type of information they are seeking at the moment.
Individuals with cognitive disabilities may find it easier to ask for what they want than to deduce its location from categorical choices.
Individuals with low vision or blindness may find search techniques that fetch everything that relates to a topic of interest to be easier than techniques that require them to scan lists or pages for the items.

Examples of Checkpoint 2.4 (Informative)

Example 1: a physics dissertation.

A dissertation contains well-defined sections such as "Abstract," "Table of Contents," "Chapter 1," etc. The pieces in each section (paragraphs, subheadings, quotes) are denoted with structural markup.
Example 2: a scalable image of a bicycle.

Lines and a circle (spokes and rim) are grouped into a "wheel." Lines in a triangle that attach to each wheel are grouped into a "frame."
Example 3: user interface.

User interface controls are divided into organized groups.

2.5 [EXTENDED] Methods are provided to minimize error and provide graceful recovery. [was 3.5]

Required Success Criteria for Checkpoint 2.5

if an error is detected, feedback is provided to the user identifying the error.

Best Practice for Checkpoint 2.5

where possible, the user is allowed to select from a list of options as well as to generate input text directly
errors are identified specifically and suggestions for correction are provided where possible
checks for misspelled words are applied and correct spellings are suggested when text entry is required.
where consequences are significant and time-response is not important, one of the following is true
1. actions are reversible where possible
2. where not reversible, actions are checked for errors in advance
3. where not reversible, and not checkable, a confirmation is asked before acceptance

Benefits of Checkpoint 2.5 (Informative)

Individuals with writing disabilities and people with dyslexia often have difficulty writing text in forms or other places that need text input.
Individuals with speech disabilities might not be recognized properly in voice input applications.

Examples of Checkpoint 2.5 (Informative)

Example 1: a search engine.

A search engine is provided with a variety of search options for different skill levels and preferences. It includes a spell checker and offers "best guess" alternatives, query-by-example searches, and similarity searches.

Guideline 3: UNDERSTANDABLE. Make content and controls understandable to as many users as possible.

Core Checkpoints for Guideline 3

3.1 [CORE] Language of content can be programmatically determined.[was 1.6 partial]

Required Success Criteria for Checkpoint 3.1

passages or fragments of text occurring within the content that are written in a language other than the primary natural language of the content as a whole, are identified, including specification of the language of the passage or fragment.

Best Practice for Checkpoint 3.1

document attributes identify the natural language of the document.

Definitions for Checkpoint 3.1 (Informative)

natural languages: Natural languages are those used by humans to communicate, including spoken, written, and signed languages.

Benefits of Checkpoint 3.1 (Informative)

Phrases from various languages, acronyms and abbreviations are often interspersed in writing. When these phrases are identified, a speech synthesizer can voice text with the appropriate accent and pronunciation. When they are not identified, the speech synthesizer will use the default accent and pronunciation of the language on the rest of the page, which can make the phrase unintelligible. Identifying changes in language and marking abbreviations and acronyms as such will also allow a tool to ask for automatic translations of that content. When editing content, authoring tools can switch between appropriate spelling dictionaries.

Examples of Checkpoint 3.1 (Informative)

Example 1: a French phrase in an English sentence.

In the following sentence, "And with a certain je ne sais quoi, she entered both the room, and his life, forever." the French phrase "ne sais quoi" is marked as French. Depending on the markup language, English may either be marked as the language for the entire document except where specified, or marked at the paragraph level.

Extended Checkpoints for Guideline 3

3.2 [EXTENDED] The definition of abbreviations and acronyms can be unambiguously determined. [was 4.3]

Required Success Criteria for Checkpoint 3.2

acronyms and abbreviations that do not appear unambiguously in the unabridged dictionary for the language are defined the first time they appear or are available in a glossary on the site.

Editorial Note: If a standard format for doing it can be achieved, we might require that linkages to glossaries for all abbreviations and acronyms that are created by the author or site be provided. We could also recommend that linkages to any abbreviations, acronyms, etc. used by the authors also be provided. We could also have a weaker recommendation for acronyms and abbreviations appearing on the site that linkages to glossaries explaining all abbreviations acronyms, etc. that appear in any documents on the site be provided.

Best Practice for Checkpoint 3.2

a list is provided of URIs to cascading dictionaries that can or should be used to define abbreviations or acronyms.
the content has been reviewed, taking into account the following strategies for determining the definition of abbreviations and acronyms, applying them as appropriate.
1. provide a definition or link (with the first occurrence) of phrases, words, acronyms, and abbreviations specific to a particular community.
2. provide a summary for relationships that may not be obvious from analyzing the structure of a table but that may be apparent in a visual rendering of the table.
3. if contracted forms of words are used such that they are ambiguous, provide semantic markup to make words unique and interpretable.

Definitions for Checkpoint 3.2 (Informative)

complex content

Content is considered complex if the relationships between pieces of information are not easy to figure out. If the presentation of the information is intended to highlight trends or relationships between concepts, these should be explicitly stated in the summary.

Examples of complex information:

data tables,
concepts that are esoteric or difficult to understand,
content that involves several layers.

unfamiliar content

Content might be unfamiliar if you are using terms specific to a particular community. For example, many of the terms used in this document are specific to the disability community.

Benefits of Checkpoint 3.2 (Informative)

Summarizing information that is difficult to understand helps people who do not read well.
Providing a summary of the visual cues that show relationships between complex information helps people who do not use visual cues or who have difficulty using visual cues. For example, people who are completely blind do not use any visual cues, while people with dyslexia or with low vision might have difficulty interpreting visual cues.
Defining key terms and specialized language will help people who are not familiar with the topic.
Providing the expansion of abbreviations and acronyms not only helps people who are not familiar with the abbreviation or acronym but can clarify which meaning of an abbreviation or acronym is appropriate to use. For example, the acronym "ADA" stands for both the American with Disabilities Act as well as the American Dental Association.

3.3 [EXTENDED] Content is written to be no more complex than is necessary and/or supplement with simpler forms of the content. [was 4.1 and 4.2]

the content has been reviewed, taking into account the following strategies for evaluating the complexity of the content, applying them as appropriate.
1. familiarity of terms and language structure
2. reasonableness of length and complexity of sentences
3. coherence of paragraphs (and sensibility in length)
4. clarity of headings and linked text when read out of context
5. accuracy and uniqueness of page titles
6. care in the use of all-capital letters where normal sentence case might increase comprehension
7. inclusion of non-text content to supplement text for key pages or sections of the site where they felt it was appropriate.

Best Practice for Checkpoint 3.3

the content has been reviewed, taking into account the following strategies for evaluating the complexity of the content, applying them as appropriate.
1. use of sentence structures that increase understanding
  - such as active voice in languages where this form helps convey information
2. length of noun phrases
  - strings of no more than three or four nouns are easiest to understand
3. clarity of reference with pronouns and anaphoric expressions (these refer back to something already said in the text)
  - example of potential ambiguity: "Scientists study monkeys. They eat bananas."
4. correct use of conjunction forms and adverbs to make explicit the relationship between phrases or parts of the text
  - such as "and," "but," "furthermore," "not only"
5. complexity of verb tenses
  - do the tenses used in a document seem overly complicated?
6. intelligibility of verb phrases
7. familiarity of idioms or slang
8. logic in the order and flow of information
9. consequences of ambiguity or abstraction
10. improved readability of vertical lists might offer in place of long paragraphs of information
11. use of summaries to aid understanding
12. thoroughness in the explanation of instructions or required actions
13. consistency in the use of names and labels
14. clarity where the document:
  - addresses users
  - explains choices and options
  - labels options to get more information
  - instructs users how to modify selections in critical functions (such as how to delete an item from a shopping cart)
15. application of:
  - proper markup to highlight key information
  - goal-action structure for menu prompts
  - default settings (and the ease in re-establishing them)
  - two-step "select and confirm" processes to reduce accidental selections for critical functions
  - calculation assistance to reduce the need to calculate
16. testing with potential users for ease of accessibility
17. use of a controlled language
18. providing support for conversion into symbolic languages
19. adding non-text content to the site for key pages or sections specifically to make the site more understandable by users who cannot understand the text only version of the site.

Definitions for Checkpoint 3.3 (Informative)

controlled languages: Controlled languages use a restricted vocabulary taken from natural language. The purpose is to make texts easier to understand and translate. Standards generally limit words to a single meaning and prescribed part of speech. Complex syntax is avoided. Information about controlled language applications is available on the World Wide Web.
non-text content: Non-text content includes images, text in raster images, image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ASCII art, 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.

Editorial Note: Is this definition adequate?

Benefits of Checkpoint 3.3 (Informative)

All users, especially those with cognitive, learning, and/or reading disabilities benefit from the use of clear and simple writing. This should not discourage you from expressing complex or technical ideas.
Using clear and simple language also benefits people whose first language differs from your own, including those people who communicate primarily in sign language.
Sounds, graphics, videos and animations can help make concepts presented in a Web site easier to understand, especially for people with cognitive, reading, or learning disabilities or those who are unfamiliar with the language of the text of the site.

Note:

Designers need to be cautious in deciding when to use illustrations. Reading a picture is probably a learned activity that is easier for some than others. Some users skip the pictures; others read only the pictures. Designers must also recognize that visual conventions are not universal and that individuals develop their own mental schema and expectations in interpreting visual information.

Examples of Checkpoint 3.3 (Informative)

Example 1: a description of a process.

A page describes how to learn to play soccer. Each step in learning the fundamentals of the game is illustrated with a photograph of a player doing what is described in the text.
Example 2: a concrete concept.

The primary concept on a page is concrete. It is discussing Mt. Pinatubo. It includes both a description of the 1991 eruption as well as photos of the eruption and the aftermath. It links to another site that contains video and another site that contains a 3D simulation of what happened underneath the crust and within the volcano during the eruption.
Example 3: child's report of school trip.

A child went with her school on a trip to a bicycle manufacturing plant. She wrote a report for her family and friends to post to the Web. In the report, she includes the company logo as well as a picture of a bicycle on the assembly line. She links to the company Web site for more information. She includes photos she took of the plant.
Example 4: stock trading data.

A news site is comparing the performance of the economy from 3rd quarter of this year with 3rd quarter from the last 3 years. They compare prices of the most popular stocks. They present the data in a bar graph with a link to the raw data they used to create the bar graph.
Example 5: history of music.

A grandfather's hobby is listening to and playing music. He creates a Web site that includes examples of many different types of music and musical instruments. When describing specific types of music, he links to a short sound clip.

3.4 [EXTENDED] Layout and behavior of content is consistent or predictable, but not identical. [was 3.3 and 3.4]

Required Success Criteria for Checkpoint 3.4

key orientation and navigational elements (such as navigation bars) are generally found in one or two consistent locations or their locations are otherwise predictable.
where inconsistent or unpredictable responses are essential to the function of the content (e.g. mystery games, adventure games, tests, etc.) the user is warned in advance of encountering them.
wherever there are extreme changes in context, one of the following is true:
1. an easy to find setting, that persists for the site visit, is provided for the user to deactivate processes or features that cause extreme changes in context or
2. extreme changes in context are identified before they occur so the user can determine if they wish to proceed or so they can be prepared for the change

Best Practice for Checkpoint 3.4

the content has been reviewed, taking into account the additional ideas listed below:
1. place navigation bars in a consistent location whenever possible
2. similar layout for user interface components should be used for sections or whole site
3. similar user interface components should be labeled with similar terminology
4. use headers consistently
5. use templates for consistent presentation of sections or whole site
6. pages with similar function should have similar appearance and layout
7. controls that look or sound the same should be designed to act the same
8. conventions likely to be familiar to the user should be followed
9. unusual user interface features or behaviors that are likely to confuse the first-time user should be described to the user before they are encountered

Definitions for Checkpoint 3.4 (Informative)

mechanisms that cause extreme changes in context

Mechanisms that cause extreme changes in context include:

opening a new browser window unexpectedly and without any nonvisual cue (back button suddenly appears nonfunctional)
in an auditory presentation, the speaker changes with no visual cue and no notation in captions
captions that do not identify a change in speaker

Common user actions include:

mouse movements
key activation
link selection
use of browser navigation buttons (e.g. back and forward)
opening new browser windows

Common responses to user actions include:

loading a new page
exposing/concealing content based on mouse position or keyboard focus
displaying the contents of a menu (auditorily or visually)
displaying pop-up menus or windows
submitting a form

It is important that responses to user actions be predictable and sensible to the end user and that interactions are consistent, both throughout the site and with commonly used interaction metaphors used throughout the Web.

Benefits of Checkpoint 3.4 (Informative)

Individuals who are unable to detect extreme changes in context or may not realize that the context has changed are less likely to become disoriented while navigating a site. This applies to people in the following ways:
- Individuals who are blind or have low vision may have difficulty knowing when a visual context change, such as a new window popping up, has occurred. In this case, warning users of context changes in advance minimizes confusion when the user discovers that the back button no longer behaves as expected.
- Using captions to note changes in speaker is beneficial for individuals who are deaf or hard of hearing and who may be unable to discern changes in speaker for audio-only presentations.
Some individuals with low vision, with dyslexia and who have difficulty interpreting visual cues may benefit from additional cues in order to detect extreme changes in context.

Note:

Providing consistent and predictable responses to user actions is important feedback for the user. This lets them know that your site is working properly and encourages them to continue interacting with the content. When the user receives an unexpected response, they might conclude that something is wrong or broken. Some people might get so confused they will not be able to use your site.

Examples of Checkpoint 3.4 (Informative)

Example 1: a form to deactivate pop-up windows.

A checkbox is provided on a page of links to let the user select whether they want the resultant pages to appear in new windows or not.
Example 2: a warning given before a pop-up window.

At the end of a news story, several links are provided for more information. At the beginning of each link is an icon of an arrow with the text equivalent, "Link will open in new window."
Example 3: frames that do not track history making the back button behave unexpectedly.
Example 4: forms.

Editorial Note: Some of these examples are very brief. Should they be expanded and clarified with further details?

Guideline 4: ROBUST. Use Web technologies that maximize the ability of the content to work with current and future accessibility technologies and user agents.

Core Checkpoints for Guideline 4

4.1 [CORE] Technologies are used according to specification [was 5.1]

Required Success Criteria for Checkpoint 4.1

for markup, except where the site has documented that a specification was violated for backward compatibility, the markup has:
1. passed validity tests of the language (whether it be conforming to a schema, Document Type Definition (DTD), or other tests described in the specification)
2. structural elements and attributes are used as defined in the specification
3. accessibility features are used
4. deprecated features are avoided
Editorial Note: The following two success criteria seem to overlap with checkpoint 4.3. There is an open question about whether they should be deleted since checkpoint 4.3 covers programmatic interfaces.
for Application Programming Interfaces (API's), programming standards for the language are followed.
accessibility features and API's are used when available.

Best Practice for Checkpoint 4.1

Same as item #1 above, without the exception for backward compatibility.

Benefits of Checkpoint 4.1 (Informative)

A search engine is provided with a variety of search options for different skill levels and preferences. It includes a spell checker and offers "best guess" alternatives, query-by-example searches, and similarity searches.

Examples of Checkpoint 4.1 (Informative)

Example 1: structural elements.

Throughout a Web site, structural elements are not used for purposes of presentation. Likewise, presentational elements are not used for purposes of structure.
Example 2: accessible API's.

A Java applet uses the accessibility API defined by the language. Refer to the IBM Guidelines for Writing Accessible Applications Using 100% Pure Java.

Extended Checkpoints for Guideline 4

4.2 [EXTENDED] Technologies that are relied upon by the content are declared and widely available.[was 5.2]

Required Success Criteria for Checkpoint 4.2

the Web resource includes a list of the technologies users must have in order for its content to work as intended. Users who do not have one or more of these technologies can still access and use the resource, though the experience may be degraded.

Note:

When determining your list of technological requirements, consider that assistive hardware and software is often slow to adapt to technological advances, and the availability of assistive technology varies across natural languages. Verify that assistive technology compatible with the technologies you choose is available in the natural language(s) of your content.

Editorial Note: This checkpoint is currently in the set of extended checkpoints. The implications of this are that there is no core checkpoint that says content must transform gracefully or that it must be backwards compatible. However, if the set of core checkpoints is designed well, core conformance would result in content that transforms gracefully. This checkpoint might be too subjective or difficult to test and may be deleted.

Best Practice for Checkpoint 4.2

a list of technologies and features, support for which is required in order for the content to be operable, has been determined and is documented in metadata and / or a policy statement associated with the content.
Technologies and features on the required list are available in at least two independently-developed implementations.
of at least two such implementations, it is true that the technologies and features on the required list have been supported by at least one prior version of the software.

Definitions for Checkpoint 4.2 (Informative)

Editorial Note: A definition of "widely available" should be added here to include something which is low cost and available in many?/most? countries/languages.

technology

A technology is a

markup or programming language
application Programming Interface (API)
or communication protocol

feature

A feature is a specific component of a technology, for example an element in a markup language or a function call in an Application Programming Interface. Typically, a given feature may only be available in specific versions of the technology, and thus may need to be noted explicitly in the required list.

Benefits of Checkpoint 4.2 (Informative)

Benefits of determining and documenting baseline user agent requirements:

Individuals can identify (either through site documentation or automatically through metadata) whether or not they are likely to be able to use a site. In conjunction with a search engine or a proxy server, this could be used to automatically filter out sites a user ~~can not~~ cannot access or to automatically filter to the top sites that would be most usable.
Requiring sites to document their baseline will cause them to evaluate assumptions about user agents and will minimize the number of sites that are inadvertently inaccessible because they are unaware of backward compatibility issues.

Benefits of designing for backward compatibility:

Individuals who must use alternative browsing technologies and devices will be able to access the content.
Individuals who ~~can not~~ cannot afford or otherwise do not have access to newer technologies also benefit from backward compatibility in that they will not need to purchase upgrades or equipment as often.

Examples of Checkpoint 4.2 (Informative)

Example 1: an online store.

By documenting minimum user agent requirements, the store makes it possible for people using particular technologies to determine if they are going to have trouble using the store or its checkout mechanism without having to go through the entire process of shopping and checkout only to find out that they are unable to complete their transaction at the end. They can, therefore, shop at stores they can be successful at.
Example 2: an Intranet site.

A large company was concerned about the ability to address individuals at many diverse sites that have different technology bases. They have, therefore, created two versions of their content and documented the requirements for each, making it easy for individual sites to determine which version would work for their technologies.

4.3 [EXTENDED] Technologies used for presentation and user interface support accessibility or alternate versions of the content are provided that do support accessibility.[was 5.3 and 5.4]

Required Success Criteria for Checkpoint 4.3

Editorial Note: The WCAG WG is considering whether to delete this checkpoint because it is about the development process rather than about the characteristics of accessible content. What are the implications of deleting this checkpoint? Should there be any checkpoints related to the development process?

the technology or combination of technologies chosen:
1. support device independence
2. include accessibility features
3. have publicly documented interfaces for interoperability
4. make use of operating system accessibility features (either directly or via the user agent) supported by assistive technologies in the natural language(s) of the content
5. are implemented in user agents and/or proxies in the natural language(s) of the content
any applications with custom user interfaces conform to at least Level A of the User Agent Accessibility Guidelines 1.0. If the application cannot be made accessible, an alternative, accessible solution is provided.

Note:

Many of the items listed in 4.3 are ambiguous and/or not actually required for accessibility. We should carefully examine this one. For example:

What does device independence mean besides the items that are already required in these guidelines?
What does "include accessibility features" mean besides what is included in this set of guidelines?
Having interfaces for interoperability publicly documented simply means that they have been posted on a Web site, it doesn't necessarily mean that it follows any standards or that anybody supports it and it doesn't necessarily make something accessible to anyone.
Unless these operating system features are all listed specifically in this standard, they should not be at a "required" level in the standard.

Cynthia has re-written this section and we should look at her recommendations carefully. These notes are based off our April 29, 2003 draft.

Best Practice for Checkpoint 4.3

the interface has been tested using a variety of assistive technologies and preferably real people with disabilities who use assistive technologies to determine that assistive technologies can access all information on the page or hidden within the page.

Editorial Note: It would be possible to comply with the checkpoint without carrying out tests (either with users or with assistive technologies). Conversely, it is possible to conduct tests, but still fail to meet the checkpoint (with respect to assistive technologies that were not tested, for example). Should this success criterion be deleted?
accessibility conventions of the markup or programming language (API's or specific markup) are used

Benefits of Checkpoint 4.3 (Informative)

Authors who utilize technologies designed to support accessibility will:
- encounter fewer challenges when implementing these guidelines
- avoid the need to create custom solutions and workarounds to address accessibility concerns
- avoid the need to provide accessible alternate versions for content rendered in a technology that does not fully address these guidelines
Individuals who rely on assistive technologies to access the Web will be able interact with the content.
Individuals who access the Web with older technologies or alternative browsing devices such as PDAs and cell phones also benefit from the inclusion of accessible alternatives to custom user interfaces.

Web Content Accessibility Guidelines 2.0

W3C Working Draft 24 June 2003

Abstract

Status of this Document

Table of Contents

Appendices

Introduction

Purpose

How to read this document

1 - Top layer First Layer—Overview of Design Principles, Guidelines, Checkpoints

2 - Second Layer—Technology-specific Checklists

3 - Bottom layer - Technology-specific application information Third Layer—Techniques

Audience

Scope

Priorities and Techniques

Conformance

Conformance Claims

Sites that conform to WCAG 1.0

Overview of Design Principles

User needs

Designing Accessible Web Content

Guideline 1: PERCEIVABLE. Make Content Perceivable by Any User

Core Checkpoints for Guideline 1

1.1 [CORE] All non-text content that can be expressed in words has a text equivalent of the function or information that the non-text content was intended to convey. [was 1.1]

Required Success Criteria for Checkpoint 1.1

Best Practice for Checkpoint 1.1

Definitions for Checkpoint 1.1 (Informative)

Benefits of Checkpoint 1.1 (Informative)

Examples of Checkpoint 1.1 (Informative)

1.2 [CORE] Synchronized media equivalents are provided for time-dependent presentations. [was 1.2]

Required Success Criteria for Checkpoint 1.2

Best Practices for Checkpoint 1.2

Definitions for Checkpoint 1.2 (Informative)

Benefits of Checkpoint 1.2 (Informative)

Examples of Checkpoint 1.2 (Informative)

1.3 [CORE] Both [information/substance] and structure are separable from presentation. [was 1.3]

Required Success Criteria for Checkpoint 1.3

Definitions for Checkpoint 1.3 (Informative)

Benefits of Checkpoint 1.3 (Informative)

Examples of Checkpoint 1.3 (Informative)

1.4 [CORE] All characters and words in the content can be unambiguously decoded. [was 1.6]

Required Success Criteria for Checkpoint 1.4

Best Practice for Checkpoint 1.4

Benefits of Checkpoint 1.4 (Informative)

Examples of Checkpoint 1.4 (Informative)

Extended Checkpoints for Guideline 1

1.5 [EXTENDED] Structure has been made perceivable to more people through presentation(s), positioning, and labels. [was 1.4]

Kill "to more people". It does not add to the statement.

Required Success Criteria for Checkpoint 1.5

Best Practices for Checkpoint 1.5

Considerations

Benefits of Checkpoint 1.5 (Informative)

Examples of Checkpoint 1.5 (Informative)

1.6 [EXTENDED] Foreground content is easily differentiable from background for both auditory and visual default presentations. [was 1.5]

Required Success Criteria for Checkpoint 1.6

Best Practice for Checkpoint 1.6

Benefits of Checkpoint 1.6 (Informative)

Examples of Checkpoint 1.6 (Informative)

Guideline 2: OPERABLE. Ensure that Interface Elements in the Content are Operable by Any User

Core Checkpoints for Guideline 2

2.1 [CORE] All functionality is operable at a minimum through a keyboard or a keyboard interface. [was 2.1]

Required Success Criteria for Checkpoint 2.1

Best Practice for Checkpoint 2.1

Definitions for Checkpoint 2.1 (Informative)

Benefits of Checkpoint 2.1 (Informative)

Examples of Checkpoint 2.1 (Informative)

2.2 [CORE] Users can control any time limits on their reading of , interaction with, or responses to appropriate content unless control is not possible due to nature of real time events or competition. [was 2.2]

Required Success Criteria for Checkpoint 2.2

Best Practice for Checkpoint 2.2

Definitions for Checkpoint 2.2 (Informative)

Benefits of Checkpoint 2.2 (Informative)

Examples of Checkpoint 2.2 (Informative)

2.3 [CORE] User can avoid experiencing screen flicker. [was 2.3]

Required Success Criteria for Checkpoint 2.3

Best Practice for Checkpoint 2.3

Benefits of Checkpoint 2.3 (Informative)

Extended Checkpoints for Guideline 2

2.4 [EXTENDED] Structure and/or alternate navigation mechanisms have been added to facilitate orientation and movement in content. [was 3.1 and 3.2]

Required Success Criteria for Checkpoint 2.4

Best Practice for Checkpoint 2.4