HTML techniques for WCAG 2.0 Success Criteria

This document shows HTML techniques for the WCAG guidelines.

Guideline HTML Techniques
Principle 1: Content must be perceivable.
1.1: For non-text content, provide text equivalents that serve the same purpose or convey the same information as the non-text content, except when the sole purpose of the non-text content is to create a specific sensory experience (for example, music and visual art) in which case a text label or description is sufficient.  
Level 1 : Text-equivalents are explicitly associated with non-text content, except when the non-text content is intended to create a specific sensory experience (for example, music without words and visual art).
Level 1 : Non-text content that is designed to create a specific sensory experience (such as music without words or visual art) has a text label or a text description explicitly associated with it.
Level 3 : A text document (for example, a movie script) is provided that includes all important visual information, dialogue, and other important sounds.
1.2: Provide synchronized media equivalents for time-dependent presentations.  
Level 1 : An audio description of visual events is provided for audio-visual media.  
Level 1 : Captions are provided for all significant dialogue and sounds in time-dependent material.  
Level 1 : Descriptions and captions are synchronized with the events they represent.  
Level 1 : If the Web content is real-time video with audio, real-time captions are provided.  
Level 1 : If the Web content is real-time, non-interactive video (for example, a Webcam view of surrounding conditions such as weather information), then one of the following is provided:  
Level 1 : If a presentation that contains only audio or only video requires users to respond interactively at specific times during the presentation, then a synchronized equivalent presentation (audio, visual or text) is provided.  
Level 2 : Synchronized captions are provided for all real-time broadcasts.  
1.3: Ensure that information, functionality, and structure are separable from presentation.  
Level 1 : Structures and relationships within the content can be derived programmatically.
Level 1 : Emphasis can be derived programmatically.
Level 1 : Any information presented through color is also available without color (for example, through context or markup or coding that does not depend on color).  
Level 2 : Information presented using color is also available without color and without having to interpret markup (for example through context or text coding).  
1.4: In visual presentations, make it easy to distinguish foreground words and images from the background.  
Level 1 : Any text that is presented over a background is electronically available so that it could be re-presented in a form that allows the text to be distinguished from the background.  
Level 2 : Text that is presented over a background has a contrast greater than ____ between the text and the background as measured by ___ or the resource provides a mechanism to allow the text to meet this criterion.  
Level 3 : This item should read identically to level 2 item #1, except that it should say "in default presentation mode."  
Level 3 : Text is not presented over a background image or pattern, or if a background image or pattern is present, the text is easily readable when the content is viewed in grayscale to determine if the background makes it difficult to identify individual characters.  
1.5: In auditory presentations, make it easy to distinguish foreground speech and sounds from background sounds.  
Level 3 : Audio content does not contain background sounds OR the background sounds are at least 20 decibels lower than the foreground audio content with the exception of occasional short sounds.  
Principle 2: Interface elements in the content must be operable.
2.1: Make all functionality operable via a keyboard or a keyboard interface.  
Level 1 : All of the functionality of the content, where the functionality or its outcome can be described in a sentence, is operable through a keyboard or keyboard interface.
Level 2 : Wherever a choice between input device event handlers is available and supported, the more abstract event is used.
Level 3 : All of the functionality of the content is operable via a keyboard or keyboard interface.
2.2: Allow users to control time limits on their reading or interaction unless specific real-time events or rules of competition make such control impossible.  
Level 1 : Content is designed so that time limits are not an essential part of interaction, or at least one of the following is true for each time limit:
Level 2 : The user is allowed to turn off content that blinks for more than 3 seconds.  
Level 2 : The user is allowed to pause and/or permanently stop moving or time-based content.  
Level 3 : The content has been designed in a way that any time limits in the content would pass level 1, success criteria 1 for this guideline without exceptions.  
Level 3 : Any non-emergency interruptions, such as the availability of updated content, can be postponed and/or suppressed by the user.  
2.3: Allow users to avoid content that could cause photosensitive epileptic seizures.  
Level 1 : Content that violates General Flash Threshold or Red Flash Threshold is marked in way that the user can access prior to its appearance.  
Level 2 : Content does not violate the General Flash Threshold or Red Flash Threshold.  
Level 3 : Content does not violate any of the Spatial Pattern Thresholds.  
2.4: Facilitate the ability of users to orient themselves and move within the content.  
Level 2 : Different structural elements look or sound different from each other and from body text.
Level 2 : In documents greater than 50,000 words or sites larger than 50 perceived pages, at least one of the following is provided.
Level 2 : Large blocks of material that are repeated on multiple pages, such as navigation menus with more than 8 or more links, can be bypassed by people who use screen readers or who navigate via keyboard or keyboard interface.
Level 3 : Information is provided that would indicate at least one logical sequence in which to read a document.
Level 3 : Diagrams are constructed so that they have structure that users can access.
Level 3 : Logical tab order has been created.
Level 3 : There is a statement associated with the content asserting that items from the following list were considered:
Level 3 : Structural emphasis is evident on at least the following displays: black and white monitor, low resolution screens (160 x 160 pixels), "mono" audio playback devices.  
2.5: Help users avoid mistakes and make it easy to correct them.  
Level 2 : If a user error is detected, the error is identified and provided to the user in text  
Level 2 : If a user error is detected, and suggestions for correction are known and can be provided without jeopardizing security or purpose (for example, test validity), they are provided (in an accessible form that meets Level 1 success criteria).  
Level 2 : Where consequences are significant and time-response is not important, one of the following is true:  
Level 3 : Where the input options are known, there are less than 75 of them, and they can be provided without jeopardizing security, test validity, etc, users are allowed to select from a list of options as well as to enter text directly.  
Level 3 : Checks for misspelled words are applied and correct spellings are suggested when text entry is required.  
Principle 3: Content and controls must be understandable.
3.1: Ensure that the meaning of content can be determined.  
Level 1 : The natural language of the document as a whole can be identified by automated tools.
Level 1 : The meaning of abbreviations and acronyms can be programmatically located.
Level 2 : Page titles are informative.  
Level 2 : The meanings and pronunciations of all words in the content can be programmatically located.  
Level 2 : The meaning of all idioms in the content can be programmatically determined.  
Level 2 : For each foreign language passage or phrase in the body of the content, the language is identified through markup or other means. Foreign passages or phrases are passages or phrases that are in a language other than the primary language of the document.
Level 3 : The meaning of contracted words can be programmatically determined.  
Level 3 : Where a word has multiple meanings and the intended meaning is not the first in the associated dictionary(s), then additional markup or another mechanism is provided for determining the correct meaning.  
Level 3 : Section headings and link text are understandable when read by themselves as a group (for example, in a screen reader's list of links or a table of contents).  
Level 3 : There is a statement associated with the content asserting that the Strategies for Reducing the Complexity of Content (the following list) were considered.  
3.2: Organize content consistently from "page to page" and make interactive components behave in predictable ways.  
Level 1 : Any extreme change of context is implemented in a manner that can be programmatically identified.
Level 2 : Components that are repeated on multiple "pages" within a resource or a section of a resource occur in the same sequence each time they are repeated, for at least one presentation format.  
Level 2 : All user interface components should be able to receive focus without causing activation.  
Level 2 : Changing the setting of any input field should not automatically cause an extreme change in context such as leaving the "page."  
Level 2 : Interactive elements that appear on multiple "pages," including graphical elements, are associated with the same functionality wherever they appear.  
Level 2 : Explicit notice is given in advance of any extreme change of context.  
Level 3 : The target of each link is clearly identified.
Level 3 : Graphical components that appear on multiple pages, including graphical links, are associated with the same text equivalents wherever they appear.  
Level 3 : Components that appear visually on multiple pages, such as navigation bars, search forms, and sections within the main content, are displayed in the same location relative to other content on every page or screen where they appear.  
Level 3 : When components such as navigation menus and search forms appear on multiple pages, users can choose to have those elements presented in a different visual position or reading-order.  
Level 3 : There are no extreme changes of context.  
Principle 4: Content must be robust enough to work with current and future technologies.
4.1: Use technologies according to specification.  
Level 1 : Except where the site has documented that a specification was violated for backward compatibility or compatibility with assistive technology, the technology has:
Level 3 : Technologies are used according to specification without exception.
4.2: Ensure that user interfaces are accessible or provide an accessible alternative(s)  
Level 1 : At least one plug-in required to access the content conforms to at least the default set of conformance requirements of the User Agent Accessibility Guidelines (UAAG) 1.0 at Level A plus the sets of requirements (a) through (j) (below) that apply. If required plug-ins are not accessible, an alternative solution is provided that conforms to WCAG 2.0. If inaccessible plug-ins are available, then a method for obtaining an accessible plug-in is provided from the content.
Level 1 : Any programmatic user interface components of the content conform to at least the default set of conformance requirements of the UAAG 1.0 at Level A plus the sets of requirements (a) through (j) (below) that apply. If the custom user interfaces cannot be made accessible, an alternative solution is provided that meets WCAG 2.0 (including this provision) to the level claimed.  
Level 2 : Accessibility conventions of the markup or programming language (API's or specific markup) are used.  
Level 3 : The Web resource includes a list of the technologies user agents must support in order for its content to work as intended. The list is documented in metadata if such metadata is supported by the format, otherwise it is documented in a policy statement associated with the content.  
Level 3 : Users who do not have one or more of these technologies can still access and use the resource, though the experience may be degraded.  
Level 3 : Technologies and features on the required list are open standards or have a public specification.