How Compliance with
Mobile Web Best Practices 1.0
Can Help Users with Disabilities

Some users, for example those with motor disability, are unable to use a mouse even when the context of use allows one. These persons often use only a keyboard or a device that emulates a keyboard. This situation parallels that of all users of mobile devices as these are not usually equipped with a mouse. They also also help people with visual disabilities who can not see the screen well and for those with short-term memory loss or cognitive limitations. Access keys may be helpful for all keyboard users. They are especially (perhaps only) useful when the browser allows the user to discover the keys that are assigned (some do, some don't).

The BP mentions that “Auto-refreshing pages are widely recognized as presenting accessibility problems” but does not explain why. Auto-refresh is especially confusing to users of screen readers. When a page is refreshed a screen reader may begin reading the updated content again from the beginning, causing confusion and preventing the user from ever reading the whole page. It is also a barrier for users of screen magnification, and those with cognitive and reading disabilities. Providing a means to stop auto-refresh may help these users if they are aware of it.

As described in the explanation of [MINIMIZE_KEYSTROKES] below, this BP is especially beneficial to users with limited dexterity. It is not related to any specific WCAG success criterion.

Readability is compromized when there is a lack of contrast with or without a background image. This BP helps users with low vision or color vision deficit (color blindness). Poor readability due to interference by patterns in background images is especially problematic for users with low vision.

Like all users of the small keypads found on mobile devices, users with motor disability may experience special difficulty in using the keyboard or other device to navigate between links. Users with cognitive disability may have difficulty concentrating on large numbers of links. Screen reader users may also have difficulty reading through and remembering a large number of links in order to decide which one they want. Given that human memory can only hold a limited number of items then having to recall more than that many links to choose the right one leads to serious difficulty for blind users. Reducing the number of links helps avoid these difficulties.

Putting the main content first helps keyboard-only users whether in a mobile context or not. It may also help users with cognitive disabilities who have difficulty locating the central information in a page full of navigation links. Users who can only read part of the page at a time, and who tend to start at the beginning, such as those using screen readers or screen magnifiers benefit from this BP.

It may lead to a writing style that also helps users with innate (rather than contextual) reading difficulties. It will help people who enlarge text or use screen magnification and therefore can not see as much of screen as intended.

Adequate color and brightness contrast make content more readable for people with low vision.

For screen reader users who are unable to visually determine the relationship between controls and their labels, it enables assistive technology to determine from markup which label identifies each form control.

If controls are not explicitly associated with their labels (as described under CONTROL_LABELLING in this document) screen readers and who use modified screens use the position in markup of the control and the label to determine the relationship. However, for recent screen readers this is now unnecessary if there is explicit association.

While this BP is primarily motivated by the limitations of the input mechanism of the mobile device (for example, a small numeric keypad), it also helps users who have difficulty using their chosen input device. Refer also to PROVIDE_DEFAULTS in this document.

Many users, but especially those with cognitive disabilities or even those with limited experience may have difficulty understanding default error messages and deciding on the correct action to take. This BP aids understanding and navigations.

Many users do not see fonts-related styling. For example, blind users, those who turn off stylesheets, or use text mode browsers. If information is conveyed by fonts, these users may have difficulty understanding the meaning of content. Refer also STYLE_SHEETS_SUPPORT in this document.

As the BP says “It is important to identify where a link leads so users can make an assessment of whether following it will be of interest to them”. While this is true for any user, some users with disabilities may have greater difficulty in judging whether the retrieved content is what they expected and of returning to the location of the link in the previous page. Refer to “Link text not descriptive” in Summary of Experience of Content Features by Users section.

In addition to the benefits described in the BP, using relative units of measure helps people with low vision by letting them increase text size in content so that they can read it.

While mobile devices have input devices such as numeric keypads that are awkward to use for text input. This BP is especially beneficial to users with limited dexterity who find text input even more difficult. It is not related to any specific WCAG 2.0 success criterion.

Implementing this BP benefits users of screen magnifiers and others who have a restricted field of vision as it ensures that they are more easily able to locate the main content of the page. Users with a motor disability or who use the keyboard for navigation will be able to view the main content of the page without difficult scrolling.

Refer to Understanding Success Criterion 3.2.3.

While correctly designed and labeled frames are not inaccessible, equivalent content without frames is generally easier to use. It is easier to scan the whole content with a screen reader and to navigate with the keyboard.

Providing text equivalents for non-text content ensures flexibility. Text can be rendered in a diversity of ways such as speech, braille, print, different text sizes. Designing content to be useful when rendered text-only (as required by the BP) requires the provision of text equivalents for non-text content and so may make content more accessible to users unable to see images or other non-text content for whatever reason. Refer to WCAG 2.0 Specific Benefits of Success Criterion 1.1.1 for further information.

Users with some disabilities may not be able or willing to install or use the plugins necessary for embedded objects. Others may be unable or unwilling to use script. Some assistive technology may not support scripting or it may be disabled.

Smaller pages may help users with cognitive limitations who have difficulty with large amounts of text.

People with visual disabilities will benefit from being able to differentiate content when multiple Web pages are open. For example, screen reader users may not be able to see at a glance the content of a window, and so identify it by the page title. People with cognitive disabilities, limited short-term memory and reading disabilities also benefit from the ability to identify content by its title. A descriptive page title also benefits people with severe mobility impairments whose mode of operation relies on audio when navigating between Web pages. Refer to Long page title, with generic information first and differentiating information last.

Opening new windows or changing between open windows when the user is not aware what is happening can be confusing to those who can not see that a new or different window has opened, or can not see the window at all. The user may not understand why the back button does not work correctly (the new window has no history or different history list) and may close the last window of the browser instance and close the application inadvertently.

While this BP is primarily motivated by the limitations of the input mechanism of the mobile device (for example, a small numeric keypad), it also helps users who have difficulty using their chosen input device.

Like auto-refresh, using markup for redirection can confuse users, especially:

• Users who have difficulty concentrating attention, who may become confused when the content changes.
• People who read slowly may not have understood what is happening before they have finished reading.
• Screen readers may begin reading the page from the beginning, only to be interrupted by redirect or auto-refresh.

This enhances accessibility for users who have difficulty scrolling for whatever reason (device or physical limitation). Limiting scrolling to one direction (particularly the vertical axis), may help people with cognitive limitations. If scrolling is necessary some may not be aware of this; others may be disoriented by horizontal scroll.

Most visual users are able to scan a whole document at a glance. Many non-visual (for example, blind) users are unable to do this and access content starting at the top. When a document is structured with section headings a screen reader or suitable browser can create a table of contents on the fly. A browser may allow keyboard navigation between headings. Refer to WCAG 1.0 HTML Techniques: Section headings for more information.

When content is organized logically, it will be rendered in a meaningful order when style sheets are turned off or not supported. This particularly helps disabled users who access pages in alternative modes. For example, blind users who use screen readers to access pages in audio, or users with low vision who use screen magnifiers. Visual font effects defined in CSS can not be relied upon a mobile device and many users may not perceive them, for example blind users who use screen readers and users with low vision who substitute authors' stylesheet with a personal stylesheet. For further information, refer to WCAG 2.0 Specific Benefits of Success Criterion 1.3.1 and the explanation of the [FONTS] best practice in this document.

Using CSS allows separation of content and presentation, enabling users to adjust presentation to suit their needs. Users with different disabilities benefit from this as it gives flexibility to user agents to adapt content according to the needs of individual users. For example, people with low vision can use their own stylesheets to change font sizes and background colours to meet their needs.

While the mobile user may not have a pointing device available a user with (for example) motor disability may need to use the keyboard for navigation. Refer to “Focus (tab) order does not match logical document content sequence” in the accompanying document “Experiences Shared by People with Disabilities and by People Using Mobile Devices”.

Reading order: Using tables can cause incorrect reading order (when the apparent visual sequence is not the same as that in the markup). Avoiding tables for layout avoids the problem. Flexibility: if content is formatted with CSS positioning, users can modify layout to suit their needs; with tables the content is locked in a grid.

Nested tables can be problematic for users of screen readers. As the screen reader is unable to differentiate between a data table (which conveys meaning) and a layout table (which should not), a screen reader may announce to the user each new table it encounters, and information such as the number of rows and columns the table contains. If tables are nested this can easily result in an excess of information and cause confusion. This best practice avoids the problem.

This BP is concerned with the characteristics of different devices, not different users, and as such does not specifically improve accessibility for users with disabilities. However, it does also encourage content providers to also test “with specific features disabled, such as using text-only modes and with scripting disabled”. This is a way of checking compliance with WCAG 1.0 checkpoints 1.1, “Provide a text equivalent for every non-text element...” and 6.3, “Ensure that pages are usable when scripts, applets, or other programmatic objects are turned off or not supported”.

Tip: You can improve accessibility when performing testing by involving users with a range of abilities (not only evaluation and development staff). Refer to the WAI resource “Involving Users in Web Accessibility Evaluation” for more information.

Users with motor disability who type URIs using the keyboard or use voice input, or who have dyslexia, may experience difficulty when entering long strings of text. Long URIs can also confuse screen reader users as the page URI is often the first thing they hear. Keeping the URIs short helps all these users. This BP deals with an aspect not considered in WCAG 1.0.

This BP benefits people with visual disabilities. Users may not be able to see colors or identify them correctly (color deficit, color blindness) or see the page at all (blind users). Users may have turned off the style sheet or use a browser that does not support CSS, or may need to use a special style sheet. These users may misinterpret or not perceive information expressed by color alone.

From WCAG 2.0, 4.1.1 Parsing: Ensuring that Web pages have complete start and end tags and are nested according to specification helps ensure that assistive technologies can parse the content accurately and without crashing. Assistive technologies used by disabled users can provide more accurate presentation of pages that validate to published grammars.