One guideline a day » Principle 2: Operable

Guideline 2.4: Focus on Information Architecture

Olga Revilla — Tue, 12 Jan 2010 11:20:42 +0000

Provide ways to help users navigate, find content, and determine where they are

Finding the content and keeping track of our location are usually difficult tasks for people with disabilities, especially for those who use screen reader or cognitive disabilities. So these criteria are made for them.

Additional, Advisory Techniques

Limit the number of links per page
Provide mechanisms to navigate to different sections of the content of a Web page
Make links visually distinct

Criterion 2.4.1 Bypass Blocks

A mechanism is available to bypass blocks of content that are repeated on multiple Web pages.

How to. Mandatory techniques

Create links to skip blocks of repeated material

Choose one of these possibilities:

Add a link at the top of each page that goes directly to the main content area
Add a link at the beginning of a block of repeated content to go to the end of the block
Add links at the top of the page to each area of the content

Group blocks of repeated material in a way that can be skipped

Choose one of these possibilities:

Provide heading elements at the beginning of each section of content
Uee structural elements to group links
Use frame elements to group blocks of repeated material and the title attribute of the frame and iframe elements
Use an expandable and collapsible menu to bypass block of content

Additional, Advisory Techniques

Provide keyboard access to important links and form controls
Provide skip links to enhance page navigation
Provide access keys
Use accessibility supported technologies which allow structured navigation by user agents and assistive technologies
Position content based on structural markup

Criterion 2.4.2 Page Titled

Web pages have titles that describe topic or purpose

How to. Mandatory techniques

Provide descriptive titles for Web pages and provide a title to each web page

Additional, Advisory Techniques

Identify a Web page’s relationship to a larger collection of Web pages
Use a technology-specific technique
Identify the subject of the Web page
Use ARIA described by property to provide a descriptive, programmatically determined label
Provide a meaningful name for
Identify frames
Use unique titles for Web pages
Provide a descriptive top-level page heading

Common Failures

The title of the Web page don’t identify the contents like “Untitled Document” or similar;
Using he same title for different pages

Criterion 2.4.3 Focus Order

If a Web page can be navigated sequentially and the navigation sequences affect meaning or operation, focusable components receive focus in an order that preserves meaning and operability.

How to. Mandatory techniques

Place the interactive elements in an order that follows sequences and relationships within the content
Give focus to elements in an order that follows sequences and relationships within the content. Choose one of these possibilities:
- Create a logical tab order through links, form controls, and objects
- Make the DOM order match the visual order
Change a Web page dynamically
- Insert dynamic content into the Document Object Model immediately following its trigger element
- Create Custom Dialogs in a Device Independent Way
- Reorder page sections Use the Document Object Model

Additional, Advisory Techniques

Provide a highly visible highlighting mechanism for links or controls when they receive keyboard focus
Create alternative presentation orders

Common Failures

Using tabindex to create a tab order that does not preserve meaning and operability
Using dialogs or menus that are not adjacent to their trigger control in the sequential navigation order

Criterion 2.4.4 Link Purpose (In Context)

The purpose of each link can be determined 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 ambiguous to users in general.

How to. Mandatory techniques

Provide link text that describes the purpose of a link, a link for anchor elements or area elements of image maps
Allow the user to choose short or long link text by a control near the beginning of the Web page that changes the link text or changing the link text by scripting
Identify the purpose of a link using link text combined with the text of the enclosing sentence
Provide a supplemental description of the purpose of a link with the title or hiding a portion of the link text by css.
Identify the purpose of a link using link text combined with programmatically determined link context. Choose one of these options:
- Enclosing list item
- Enclosing paragraph
- HEnclosing table cell and associated table headings
- Preceding heading element
- In a nested list, link text combined with the parent list item under which the list is nested

Additional, Advisory Techniques

Combining adjacent image and text links for the same resource
Use ARIA described by property to provide a descriptive, programmatically determined label

Common Failures

Providing link context only in content that is not related to the link
Using null alt on an image where the image is the only content in a link

Criterion 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

How to. Mandatory techniques

Use 2 or more of these techniques

Provide links to navigate to related Web pages
Provide a Table of Contents
Provide a site map
Provide a search function to help users find content
Provide a list of links to all other Web pages
Linking to all of the pages on the site from the home page

Additional, Advisory Techniques

Use the link element and navigation tools
Include information about presentation modes in tables of contents and concept maps

Criterion 2.4.6 Headings and Labels

Headings and labels describe topic or purpose

How to. Mandatory techniques

Provide descriptive headings
Provide descriptive labels

Additional, Advisory Techniques

Use unique section headings in a Web Page
Start section headings with unique information

Criterion 2.4.7 Focus Visible

Any keyboard operable user interface has a mode of operation where the keyboard focus indicator is visible.

How to. Mandatory techniques

Use user interface components that are highlighted by the user agent when they receive focus
Use CSS to change the presentation of a user interface component when it receives focus
Use the default focus indicator for the platform so that high visibility default focus indicators will carry over
Use an author-supplied, highly visible focus indicator
Use script to change the background color or border of the element with focus (Scripting)

Additional, Advisory Techniques

Highlight a link or control when the mouse hovers over it
Provide a highly visible highlighting mechanism for links or controls when they receive keyboard focus

Common Failures

using script to remove focus when focus is received
Styling element outlines and borders in a way that removes or renders non-visible the visual focus indicator

Criterion 2.4.8 Location

Information about the user’s location within a set of Web pages is available.

How to. Mandatory techniques

Provide a breadcrumb trail.
Provide a site map 3.
Indicate current location within navigation bars
Identify a Web page’s relationship to a larger collection of Web pages with the link element and navigation tools

Additional, Advisory Techniques

Provide a link to the home page or main page
Provide an easy-to-read version of information about the organization of a set of Web pages
Provide a sign language version of information about the organization of a set of Web pages
Provide an easy-to-read summary at the beginning of each section of content

Criterion 2.4.9 Link Purpose (Link Only)

A mechanism is available to allow the purpose of each link to be identified from link text alone, except where the purpose of the link would be ambiguous to users in general.

How to. Mandatory techniques

Provide link text that describes the purpose of a link for anchor elements or text alternatives for the area elements of image maps
Allow the user to choose short or long link text by a control near the beginning of the Web page that changes the link text or using scripts to change the link text
Provide a supplemental description of the purpose of a link hiding a portion of the link text with CSS

Additional, Advisory Techniques

Combine adjacent image and text links for the same resource
Support link text with the title attribute

Common Failures

Using a non-specific link such as “click here” or “more” without a mechanism to change the link text to specific text.
Using null alt on an image where the image is the only content in a link

Criterion 2.4.10 Section Headings

Section headings are used to organize the content.
Note 1: “Heading” is used in its general sense and includes titles and other ways to add a heading to different types of content.
Note 2: This success criterion covers sections within writing, not user interface components. User Interface components are covered under Success Criterion 4.1.2.

How to. Mandatory techniques

Organize a page using headings

Additional, Advisory Techniques

Use the ‘live’ property to mark live regions
Provide mechanisms to navigate to different sections of the content of a Web page

More info

Guideline 2.3: Be careful with flashing visual content

Olga Revilla — Sat, 17 Oct 2009 10:25:29 +0000

Do not design content in a way that is known to cause seizures.

3-flash-in-a-second is the lower rate recommended to show flash content for people who suffer from seizures due to photosensitivity, specially for red lights. But still there are more sensitive people that react to lower rates, so the recommendation is to eliminate this type of visual content (like in WCAG 1 checkpoint 7.2).
Another novelty is the difference between “blinking” and “fashing”:

blinking: content that distracts, and can be used for a short time as long as it stops or can be stopped by the user. If blinking occurs faster than 3 per second, it should be considered a flash.
flashing: content faster than 3 per second, and large and bright enough to cause a seizure The chance to turn the flash off is not an option since the seizure could occur faster than most users could turn it off.

How to know if your flashing content is 3 or more blinking times in a second? Try these tools:

In order to not interfere with other content of the webpage, these criteria applies for the whole page.

Criterion 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.

How to. Mandatory techniques

Ensure that no component of the content flashes more than three times in any 1-second period
Keep the flashing area small enough
Use a tool to ensure that content does not violate the general flash threshold or red flash threshold

Additional, Advisory Techniques

Reduce contrast for any flashing content
Avoid fully saturated reds for any flashing content
Reduce the number of flashes even if they do not violate thresholds
Provide a mechanism to suppress any flashing content before it begins
Slow down live material to avoid rapid flashes (as in flashbulbs)
Freeze the image momentarily if 3 flashes within one second are detected
Drop the contrast ratio if 3 flashes within one second are detected

Criterion 2.3.2 Three Flashes

Web pages do not contain anything that flashes more than three times in any one second period

How to. Mandatory techniques

Ensure that no component of the content flashes more than three times in any 1-second period

Additional, Advisory Techniques

They are the same techniques as 2.3.1

More info

Guideline 2.2: Don’t hurry up anyone

Olga Revilla — Sun, 09 Aug 2009 19:05:40 +0000

Provide users enough time to read and use content.

Imagine you are reading a webpage and, in the middle of that proccess, the page reloads and changes, so you can not finish the reading of the formerly page. Everybody needs different time to complete tasks, and this time is usually higher on the elderly and users with disabilities.

So this guideline is about eliminating time constraints or providing users enough additional time to allow them to complete their tasks.

Criterion 2.2.1 Timing Adjustable

For each time limit that is set by the content, at least one of the following is true: (Level A)

Turn off: The user is allowed to turn off the time limit before encountering it;

Adjust: The user is allowed to adjust the time limit before encountering it over a wide range that is at least ten times the length of the default setting;

Extend: The user is warned before time expires and given at least 20 seconds to extend the time limit with a simple action (for example, “press the space bar”), and the user is allowed to extend the time limit at least ten times;

Real-time Exception: 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;

Essential Exception: The time limit is essential and extending it would invalidate the activity;

20 Hour Exception: The time limit is longer than 20 hours.

This success criterion helps ensure that users can complete tasks without unexpected changes in content or context that are a result of a time limit. This success criterion should be considered in conjunction with Success Criterion 3.2.1, which puts limits on changes of content or context as a result of user action.

How to. Mandatory techniques

Situation A: If there are session time limits:

Provide a checkbox on the first page of a multipart form that allows users to ask for longer session time limit or no session time limit
Provide a way for the user to turn the time limit off

Situation B: If a time limit is controlled by a script on the page:

Provide a way for the user to turn the time limit off
Provide a means to set the time limit to 10 times the default time limit
Providing a script that warns the user a time limit is about to expire AND allow the user to extend the default time limit

Situation C: If there are time limits on reading:

Allow the content to be paused and restarted from where it was paused
Provide a way for the user to turn the time limit off
Use script to scroll content, and provide a mechanism to pause it
Provide a mechanism to allow users to display moving, scrolling, or auto-updating text in a static window or area

Additional, Advisory Techniques

Use a script to poll the server and notify a user if a time limit is present

Common Failures

Using meta redirect with a time limit
Using meta refresh with a time-out
Using server-side techniques to automatically redirect pages after a time-out
Including scrolling content where movement is not essential to the activity without also including a mechanism to pause and restart the content

Criterion 2.2.2 Pause, Stop, Hide

For moving, blinking, scrolling, or auto-updating information, all of the following are true: (Level A)

Moving, blinking, scrolling: For any moving, blinking or scrolling information that (1) starts automatically, (2) lasts more than five seconds, and (3) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it unless the movement, blinking, or scrolling is part of an activity where it is essential; and

Auto-updating: For any auto-updating information that (1) starts automatically and (2) is presented in parallel with other content, there is a mechanism for the user 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.

Notes:

For requirements related to flickering or flashing content, refer to Guideline 2.3.

Since any content that does not meet this success criterion can interfere with a user’s ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion.

Content that is updated periodically by software or that is streamed to the user agent is not required to preserve or present information that is generated or received between the initiation of the pause and resuming presentation, as this may not be technically possible, and in many situations could be misleading to do so.

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

How to. Mandatory techniques

Allowing the content to be paused and restarted from where it was paused
Use script to scroll content, and providing a mechanism to pause it
Creatie content that blinks for less than 5 seconds
Use a technology to include blinking content that can be turned off via the user agent
Set animated gif images to stop blinking after n cycles (within 5 seconds)
Use scripts to control blinking and stop it in five seconds or less (Scripting)
Use a control in the Web page that stops moving, blinking, or auto-updating content
Provide a link, button, or other mechanism that reloads the page without any blinking content

Additional, Advisory Techniques

Provide a mechanism to stop all content that blinks within a Web page
Provide the user with a means to stop moving content even if it stops automatically within 5 seconds

Common Failures

including scrolling content where movement is not essential to the activity without also including a mechanism to pause and restart the content
using the blink element
using text-decoration:blink without a mechanism to stop it in less than five seconds
a script that causes a blink effect without a mechanism to stop the blinking at 5 seconds or les
an object or applet, such as Java or Flash, that has blinking content without a mechanism to pause the content that blinks for more than five seconds

Criterion 2.2.3 No Timing

Timing is not an essential part of the event or activity presented by the content, except for non-interactive synchronized media and real-time events. (Level AAA)

How to. Mandatory techniques

Allow users to complete an activity without any time limit

Criterion 2.2.4 Interruptions

Interruptions can be postponed or suppressed by the user, except interruptions involving an emergency. (Level AAA)

How to. Mandatory techniques

Provide a mechanism to postpone any updating of content
Provide a mechanism to request an update of the content instead of updating automatically
Use scripts to make nonessential alerts optional (Scripting)

Common Failures

Using meta redirect with a time limit
Using meta refresh with a time-out

Criterion 2.2.5 Re-authenticating

When an authenticated session expires, the user can continue the activity without loss of data after re-authenticating. (Level AAA)

How to. Mandatory techniques

Provide options to continue without loss of data:

Saving data so that it can be used after a user re-authenticates; or
Encoding user data as hidden or encrypted data in a re-authorization page

Common Failures

Having a session time limit without a mechanism for saving user’s input and re-establishing that information upon re-authentication

More info

Guideline 2.1: Don’t forget users without a pointer

Olga Revilla — Wed, 03 Jun 2009 14:03:39 +0000

Make all functionality available from a keyboard

When a functionality can be achieved using only the keyboard, other input devices can be used. But, if you use only a mouse or a speech input, assistive technologies will find it difficult to operate it.

Obviously, you can use another input devices to complement the keyboard, and even you are encouraged to do it, but don’t forget that every feature must be operable by a keyboard input.

Criterion 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. (Level A)

The exception is about the underlying function, not the input technique. For example, if using handwriting to enter text, the input technique (handwriting) requires path-dependent input but the underlying function (text input) does not.

This does not forbid and should not discourage providing mouse input or other input methods in addition to keyboard operation.

How to. Mandatory techniques

Ensure keyboard control by using HTML form controls and links
Provide keyboard-triggered event handlers using both keyboard and other device-specific functions, making actions keyboard accessible by using the onclick event of anchors and buttons, or using redundant keyboard and mouse event handlers

Additional, Advisory Techniques

Use XHTML role, state, and value attributes if repurposing static elements as interactive user interface components and add keyboard-accessible actions to static HTML elements
Provide keyboard shortcuts to important links and form controls
Use unique letter combinations to begin each item of a list
Choose the most abstract event handler
Use the onactivate event
Avoid use of common user-agent keyboard commands for other purposes

Common Failures

using only pointing-device-specific event handlers (including gesture) for a function
using script to remove focus when focus is received
using scripting events to emulate links in a way that is not programmatically determinable

Criterion 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, the user is advised of the method for moving focus away. (Level A)

Since any content that does not meet this success criterion can interfere with a user’s ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion.

How to. Mandatory techniques

Ensure that users are not trapped in content

Common Failures

Combining multiple content formats in a way that traps users inside one format type

Criterion 2.1.3 Keyboard (No Exception)

All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes. (Level AAA)

How to. Mandatory techniques

This is the same as Success Criterion 2.1.1, but no exceptions are allowed. Just follow techniques for it. If there is a requirement for analog, time-dependent input, then it is not possible to meet this Criterion.