WCAG2.0 Level AA, your guide part 2

Here we will look at the WCAG2.0 Guidelines level AA. This is the second of three levels of accessibility and in the UK is considered the minimal level for all public sector organisation web services. It will help give most people a reasonable level of access although it will not neceressally give people an equal experience.

The guidelines are based on four principles POUR, see the article Get started with WCAG2.0 for an overview.

Note before you can reach WCAG2.0 Level AA you must first meet all WCAG2.0 Level A, see WCAG2.0 Level A, your guide part 1.


1.2.4 Captions (Live): Captions are provided for all live audio content in synchronized media. This is to offer an alternative text based content that is presented at the same time as the live audio for the benefit of those people who may not be able to hear the audio stream. This may include people with hearing impairments as well as people who may not have any audio device available.

1.2.5 Audio Description (Pre-recorded): Audio description is provided for all pre-recorded video content in synchronized media. This is where you add audio descriptions of any relevant visual content to the video media for the benefit of people who may not be able to see the visual content. Please note this will not address people who have difficulty with both visual and audio content. To address this a textual content such as full transcript will be required.

1.4.3 Contrast (Minimum): The visual presentation of text and images of text has a contrast ratio of at least 4.5:1, except for the following:

  • Large-scale text (18PT+ or Bold 14PT+) and images of large-scale text have a contrast ratio of at least 3:1;
  • Text or images of text that are part of an inactive user interface component, that are pure decoration, that are not visible to anyone, or that are part of a picture that contains significant other visual content, have no contrast requirement.
  • Text that is part of a logo or brand name has no minimum contrast requirement.

You can use free tools like the webaim colour checker to see if your colour contrast meets the requirements.

1.4.4 Resize text: Except for captions and images of text, text can be resized without assistive technology up to 200 percent without loss of content or functionality. This is to allow people to use the text size option of their web browser to increase the text size. It should allow text to be double it’s original size without breaking or making it difficult to read or use.

1.4.5 Images of Text: If the technologies being used can achieve the visual presentation, text is used to convey information rather than images of text except for the following:

  • The image of text can be visually customized to the user’s requirements;
  • A particular presentation of text is essential to the information being conveyed (text that is part of a logo or brand name) are considered essential.

By using textual content instead of text within images, it will allow people to adapt the text into a format that they can use. Where as text within images are not so flexible and may not be accessible to some people. Examples may include people using Braille or people with dyslexia or limited vision.


2.4.5 Multiple Ways: More than one way is available to locate a Web page within a set of Web pages except where the Web Page is the result of, or a step in, a process. This may include things like a site map, keyword search or breadcrumb. All can help people find pages within a website more easily.

2.4.6 Headings and Labels: Headings and labels describe topic or purpose. This is about how effective the use of language is to describe the relevant topic or purpose in headings and labels. This will help people quickly identify and understand the various topics and controls available to them. Short, simple, concise and relevant are what will be most effective.

2.4.7 Focus Visible: Any keyboard operable user interface has a mode of operation where the keyboard focus indicator is visible. This is about showing people where they currently are on a page when using a keyboard or other similar control device. Unlike using a mouse, where you have a pointer to show you, without this pointer, you need other visual indication such as highlighted outlines, change of colour or similar clearly marked visible indicator.


3.1.2 Language of Parts: The human language of each passage or phrase in the content can be programmatically determined except for proper names, technical terms, words of indeterminate language, and words or phrases that have become part of the vernacular of the immediately surrounding text. This is referring to any content that is in any other language other than the default language set for the page. So if the default language is in English but there is a short passage wrote in French, this will need to use mark-up that specifies that it’s in French. The purpose is to help assistive technology such as screen readers, Braille displays and others know the change of language from the default set at the beginning.

3.2.3 Consistent Navigation: Navigational mechanisms that are repeated on multiple Web pages within a set of Web pages occur in the same relative order each time they are repeated, unless a change is initiated by the user. Consistency will help people become familiar more quickly and can greatly enhance the experience for people using assistive technology.

3.2.4 Consistent Identification: Components that have the same functionality within a set of Web pages are identified consistently. If not consistent in the naming of Components across web pages, it can give confusing or conflicting information. Leading to people being frustrated, confused or simply lost.

3.3.3 Error Suggestion: If an input error is automatically detected and suggestions for correction are known, then the suggestions are provided to the user, unless it would jeopardize the security or purpose of the content. This is about helping people understand where and what mistakes they may of made. By offering support in this way, it can help people complete tasks without the need for alternative communication. It is best if the error messages are provided in text with clear indication to where the mistake was made.

3.3.4 Error Prevention (Legal, Financial, Data): For Web pages that cause legal commitments or financial transactions for the user to occur, that modify or delete user-controllable data in data storage systems, or that submit user test responses, at least one of the following is true:

  1. Submissions are reversible, meaning people can request to undo the change.
  2. Data entered by the user is checked for input errors and the user is provided an opportunity to correct them. This will give people the chance to see any mistakes and allow them to correct them before making any commitment.
  3. A mechanism is available for reviewing, confirming, and correcting information before finalizing the submission. This is giving people the chance to look over their information and choices before making a commitment and allowing them to make any changes required.
  4. Robust

    There are no level AA or AAA guidelines in the last principle, only 2 level A guidelines.

WCAG2.0 Level A, your guide part 1

Here we will look at the WCAG2.0 Guidelines level A. This is the most basic level of accessibility and without it, will prevent many people from being able to use your website. It may also impact the level of usability for everyone not just people who may have an impairment.

The guidelines are based on four principles POUR, see the article Get started with WCAG2.0 for an overview.


1.1 Text Alternatives

1.1.1 Non-text Content: Any of your web pages content that is not in regular text, such as images, video, sound, Flash or other similar content that is available to your visitors, must have a text alternative that gives an equivalent purpose, except in the cases listed below.

Regular text is any text that can be selected and understood by other technologies, such as text editors. It does not include text that is embedded into images, videos or spoken within audio. A simple test is to see if you can highlight the text and copy it into a text editor like notepad.

  • For web controls such as buttons or forms you give them text names or text labels that will explain their purpose, see WCAG2.0 4.1 for more details.
  • For time based media, the text alternative should at least give a description of the media, see WCAG2.0 1.2 for more details.
  • When providing a test or exercise in a text format would be invalidated you should at least give a description of the non text content.
  • When the primary purpose is for creating a specific sensory experience, you should at least give a description of the content.
  • When using CAPTCHAs, you should at least give a description that identifies and explains the purpose of the CAPTCHA. You should also provide alternative CAPTCHAs for different types of sensory perception. These may include, visual, audible or touch, see the article Captcha should it stay or should it go.
  • For cases when using visual effect for pure decoration or only for visual formatting, or is not to be shown to people, you should use a method that is not visible to assistive technology. Things like placing decorational images as CSS backgrounds instead of HTML image content.

1.2 Time-based Media

these guidelines do not apply when the audio or video is used as an alternative for text content and is clearly labelled as such. There is more information at WCAG2.0 Understanding Guideline 1.2.

It is worth noting that these guidelines address people with either hearing or visual impairment but do not address accessibility issues for people with both hearing and visual impairments or may not address people with cognitive impairments. Remember any time based media may effect people’s access especially for those who take more time to access and understand the content.

1.2.1 Audio-only and Video-only (Pre-recorded): An alternative for time-based media is available that gives the same information for pre-recorded audio-only content and Either an alternative for time-based media or an audio track is available that gives the same information for pre-recorded video-only content.

1.2.2 Captions (Pre-recorded): Captions are available for all pre-recorded audio content in synchronized media,.

1.2.3 Audio Description or Media Alternative (Pre-recorded): An alternative for time-based media or audio description of the pre-recorded video content is available for synchronized media.

1.3 Adaptable

1.3.1 Info and Relationships: Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text. This refers to things like HTML semantics, for an example see the article Get started with Structured Headings.

1.3.2 Meaningful Sequence: When the order in which content is given affects its meaning, a correct reading sequence can be programmatically determined. This refers to things like the tab ordering and the HTML order of content as appose to any visual layout being used. It is there to help ensure assistive technology can follow the order of information as it is intended without out loosing any meaning.

1.3.3 Sensory Characteristics: Instructions provided for understanding and operating content do not rely solely on sensory characteristics of components such as shape, size, visual location, orientation, or sound. This is to allow people to follow instructions regardless of which Sensory control they are using such as audio, visual or touch.

1.4 Distinguishable

1.4.1 Use of Colour: Colour is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element.

1.4.2 Audio Control: If any audio on a Web page plays automatically for more than 3 seconds, either a mechanism is available to pause or stop the audio, or a mechanism is available to control audio volume independently from the overall system volume level.


2.1 Keyboard Accessible

2.1.1 Keyboard: All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes, except where the underlying function requires input that depends on the path of the user’s movement and not just the endpoints. For example if using handwriting to enter text, the input technique (handwriting) requires path-dependent input but the underlying function (text input) does not. You are not advised to avoid other input methods like mouse or touch screens but instead allow for both. See the article A Little Accessibility Guide to Device Independence.

2.1.2 No Keyboard Trap: If keyboard focus can be moved to a component of the page using a keyboard interface, then focus can be moved away from that component using only a keyboard interface, and, if it requires more than unmodified arrow or tab keys or other standard exit methods, like the escape key, the user is advised of the method for moving focus away. Common examples of keyboard traps are embedded objects like Flash or JavaScript that takes control over the keyboard input.

2.2 Enough Time

2.2.1 Timing Adjustable: This helps ensure that people can complete tasks without unexpected changes in content or context that are a result of a time limit. You should not use time limits on content unless one of the following applies:

  • People are able to turn off the time limit before it starts.
  • People are able to adjust the time limit over a wide range that is at least ten times the length of the default setting and before it starts.
  • People are warned before the time limit expires and are given at least 20 seconds to extend the time limit with a simple action (for example, “press the space bar”), and they are able to extend the time limit at least ten times.
  • The time limit is a required part of a real-time event (for example, an auction), and no alternative to the time limit is possible.
  • The time limit is essential and extending it would invalidate the activity.
  • The time limit is longer than 20 hours.

2.2.2 Pause, Stop, Hide: For any moving, blinking or scrolling information that starts automatically, or lasts more than five seconds, and is not the only content available, there needs to be a way for people to pause, stop, or hide it unless it’s part of an activity where it is essential. For any auto-updating information that starts automatically and is not the only content available, there needs to be a way for people to pause, stop, or hide it or to control the frequency of the update unless the auto-updating is part of an activity where it is essential.

Content that is updated periodically by software or that is streamed to the browser is not required to keep or give information that is generated or received between the pause and resume action as this may not be technically possible, and in many cases could be misleading to do so.

An animation that occurs as part of a preload phase or similar case can be treated as essential if interaction cannot occur during that phase for all people and if not indicating progress could confuse people or cause them to think that content was frozen or broken.

2.3 Seizures

2.3.1 Three Flashes or Below Threshold: Web pages do not contain anything that flashes more than three times in any one second period, or the flash is below the general flash and red flash thresholds. This is to prevent people susceptible to photo-sensory related Seizures from having attacks provoked by your content. This will include animations, video or interactive content.

If you have any content that may not comply with this guideline, it is important that you make people aware before the content is shown and allow people to choose weather to proceed with the content.

2.4 Navigable

2.4.1 Bypass Blocks: Give people a way to bypass blocks of content that are repeated on multiple Web pages. This refers to things like skip links and is there to help people get to content more easily.

2.4.2 Page Titled: Web pages have titles that describe topic or purpose. This is both a SEO (Search Engine Optimisation) and accessibility requirement. The more relevant and concise the title the better. It should reflect the topic and purpose of the page and not the website in general.

2.4.3 Focus Order: This refers to the order in which items that can have focus like links, form fields, buttons and any control that people can interact with are placed. It is important that this order makes sense to people regardless of the device or assistive technology they may be using.

2.4.4 Link Purpose (In Context): The purpose of each link can make sense from the link text alone or from the link text together with its programmatically determined link context, except where the purpose of the link would be confusing to people in general.


3.1 Readable

3.1.1 Language of Page: The default human language of each Web page can be programmatically determined. This refers to adding a base language to the page that can be used by assistive technology and web browsers.

3.2 Predictable

3.2.1 On Focus: When any component receives focus, it does not initiate a change of context. This is to prevent any unexpected behaviour when people are moving focus from one place to another, This includes tabbing or clicking into a text field. You can read more on WCAG2.0 Understanding on focus.

3.2.2 On Input: Changing the setting of any user interface component does not automatically cause a change of context unless the user has been advised of the behaviour before using the component. This is about always informing people of any unpredictable changes, things like a link opens in a new window. As this is not the default action of a link and may cause confusion. For more information see WCAG2.0 Understanding on input.

3.3 Input Assistance

3.3.1 Error Identification: If an input error is automatically detected, the item that is in error is identified and the error is described to the user in text. When identifying errors with information entered by people, it is important to do this with text and not through images, colours or sound alone. This is to ensure it is available to everyone regardless of technology used.

3.3.2 Labels or Instructions: Labels or instructions are provided when content requires user input. This is for things like web forms, search boxes or login screens. Anywhere people need to enter information, suitable instructions and labels should be given.


4.1 Compatible

This is about following code standards and best coding practices to ensure the code will work equally well across multiple browsers and with various assistive technologies. You can see more about device independence and assistive technologies in the article A Little Accessibility Guide to Device Independence.

4.1.1 Parsing: In content implemented using markup languages, elements have complete start and end tags, elements are nested according to their specifications, elements do not contain duplicate attributes, and any IDs are unique, except where the specifications allow these features.

4.1.2 Name, Role, Value: For all user interface components (including but not limited to: form elements, links and components generated by scripts), the name and role can be programmatically determined; states, properties, and values that can be set by the user can be programmatically set; and notification of changes to these items is available to user agents, including assistive technologies.

This is primarily for Web authors who develop or script their own user interface components. For example, standard HTML controls already meet this guideline when used according to specification.


For WCAG2.0 Level A, the first and lowest level of accessibility guidelines, it has 25 different things to check. These are across all four POUR Principles and broken into guideline categories like 1.1 Text Alternatives.

You can appreciate after reading through these initial guidelines, that knowing a little about assistive technology and how people use these technologies, why the guidelines exist.

My next post will go over each of these 25 checks and explain why I believe they may or may not be tested with automated systems.

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