From WCAG 2.0 to MWBP 1.0: Making content that meets Web Content Accessibility Guidelines 2.0 also meet Mobile Web Best Practices 1.0
W3C Editor's Draft 10 October 2008
Introduction
Incomplete draft: This document is an in-progress Working Draft provided for review and feedback. It is incomplete and will likely have major changes. See also Status of this Document in the overview page.
Please send feedback to public-bpwg-comments@w3.org (with public archive).
This page is part of a multi-page document. Please refer to the “How to Use This Document” section for more information.
This page describes how some WCAG success criteria (SC) can help with achieving compliance with the Mobile Web Best Practices 1.0 (MWBP). For content that already complies with WCAG, it outlines what may need to be done to comply with each BP.
As described in this section, many SCs have the added benefit of partial or complete compliance with certain BPs. However, the best practices may describe a different aspect of the same concept. It should not be assumed that following any SC will ensure compliance with the MWBP. To ensure compliance it is important to always consult the Mobile Web Best Practices 1.0 [MWBP1.0] or the Web Content Accessibility Guidelines 2.0 [WCAG2.0].
Summary of work required to make content that meets WCAG 2.0 also meet MWBP
Compliance with WCAG 2.0 helps go some way towards achieving compliance with some of the MWBP. This section provides a summary of these BPs. There are two possible levels of effort required, labelled for simplicity with the keywords nothing, something and everything. Note that coverage may depend on WCAG compliance level achieved and so a BP may appear in “something” and “nothing” lists (for example, LINK_TARGET_ID). To summarise, if your content already complies with WCAG 2.0, to achieve compliance with the MWBP, you need to do the following:
Nothing: Content already complies with this provision so no further effort is necessary. The list is provided for completeness. Links in this section point to the relevant Recommendation.
Something: More effort of some kind is necessary to comply with the provision. What is required is explained in the following section. For each there is a list of the provisions that may provide some compliance or are in some way related. There is no direct correspondence between one provision and another. In some cases, it may be necessary to make an extra effort or to consider a more diverse range of user needs. In these cases, the word “possibly” is used. In other cases scope may be different, giving partial compliance. In these cases the word “partially” is used. BP links in this section point to the detail section below; SC links in this section point to WCAG 2.0.
- BACKGROUND_IMAGE_READABILITY, possibly covered at level AA by 1.4.3 Contrast (Minimum) and at level AAA 1.4.6 Contrast (Enhanced)
- COLOR_CONTRAST, partially covered at level AA by success criterion 1.4.3 Contrast (Minimum) and at level AAA 1.4.6 Contrast (Enhanced)
- CONTROL_LABELLING, possibly covered at level A by 1.3.1 Info and Relationships, 3.3.2 Labels or Instructions and 4.1.2 Name, Role, Value.
- CONTROL_POSITION, possibly covered at level A by 1.3.1 Info and Relationships.
- GRAPHICS_FOR_SPACING, possibly covered at level A by 1.3.1 Info and Relationships.
- LINK_TARGET_ID, partially covered at level A by 2.4.4 Link Purpose (In Context).
- MEASURES, possibly covered at level AA by 1.4.4 Resize text.
- NAVIGATION, partially covered at level AA by 3.2.3 Consistent Navigation and at level AAA 2.4.10 Section Headings.
- NON-TEXT_ALTERNATIVES, partially covered at level AAA by 1.2.7 Full Text Alternative (but covered already at that level by 1.1.1 Non-text Content).
- OBJECTS_OR_SCRIPT, partially covered at level A by 2.1.1 Keyboard and at level AAA by 2.1.3 Keyboard (No Exception).
- PAGE_TITLE, possibly covered at level A by 2.4.2 Page Titled.
- POP_UPS, partially covered at level A by 3.2.1 On Focus and 3.2.2 On Input and possibly at level AAA by 3.2.5 Change on Request.
- REDIRECTION, covered at level A by 2.2.1 Timing Adjustable and at level AAA by 2.2.4 Interruptions and 3.2.5 Change on Request.
- STRUCTURE, possibly covered at level A by success criterion 1.3.1 Info and Relationships and at level AA by 2.4.6 Headings and Labels and at level AAA by 2.4.10 Section Headings.
- VALID_MARKUP, possibly covered at level A by 4.1.1 Parsing.
Everything: For all other BPs, WCAG 2.0 does not ensure compliance and it will be necessary to do the work involved. These BPs are not related to any WCAG 2.0 success criteria.
- ACCESS_KEYS
- AVOID_FREE_TEXT
- BALANCE
- CACHING
- CAPABILITIES
- CENTRAL_MEANING
- CHARACTER_ENCODING_SUPPORT
- CHARACTER_ENCODING_USE
- CLARITY
- CONTENT_FORMAT_PREFERRED
- CONTENT_FORMAT_SUPPORT
- COOKIES
- DEFAULT_INPUT_MODE
- DEFICIENCIES
- ERROR_MESSAGES
- EXTERNAL_RESOURCES
- IMAGE_MAPS
- IMAGES_RESIZING
- IMAGES_SPECIFY_SIZE
- LARGE_GRAPHICS
- LIMITED
- LINK_TARGET_FORMAT
- MINIMIZE
- MINIMIZE_KEYSTROKES
- NAVBAR
- NO_FRAMES
- PAGE_SIZE_LIMIT
- PAGE_SIZE_USABLE
- PROVIDE_DEFAULTS
- SCROLLING
- STYLE_SHEETS_SIZE
- SUITABLE
- TABLES_ALTERNATIVES
- TABLES_LAYOUT
- TABLES_NESTED
- TABLES_SUPPORT
- TESTING
- THEMATIC_CONSISTENCY
- URIS
Addressing Mobile Web Best Practices
This section deals with each of the best practices which WCAG 2.0 helps with meeting. For each BP, the section title is that of the BP. This is followed by a list of the SCs that can help meet it.
Back to Best Practices list.
[BACKGROUND_IMAGE_READABILITY] When using background images make sure that content remains readable on the device
If overall contrast is sufficient, this goes part of the way to ensuring readability with background images.
Back to Best Practices list.
[COLOR_CONTRAST] Ensure that foreground and background color combinations provide sufficient contrast
Unlike MWBP, WCAG specifies a contrast ratio and algorithm and certain types of content that are excluded from the requirement. The following SCs may ensure compliance with this BP, if content covered by the BP is not excluded.
Back to Best Practices list.
[CONTROL_LABELLING] Label all form controls appropriately and explicitly associate labels with form controls
The following SCs ensure compliance with this BP when the label element is used for form controls.
Back to Best Practices list.
[CONTROL_POSITION] Position labels so they lay out properly in relation to the form controls they refer to
- 1.3.1 Info and Relationships at level A, possibly. The SC has an advisory (optional) technique (“Positioning labels to maximize predictability of relationships”) that may ensure compliance.
Back to Best Practices list.
- 1.3.1 Info and Relationships at level A, possibly. The SC does not prohibit the use of graphics for spacing, but some of the sufficient techniques may ensure compliance with this BP by encouraging the use of alternatives.
Back to Best Practices list.
[LINK_TARGET_ID] Clearly identify the target of each link
- 2.4.4 Link Purpose (In Context) at level A goes some way to meeting this BP, but the SC provides for indicating the link purpose in the context which is not contemplated by the BP, and in the title attribute or table cell header which are unlikely to be supported adequately by a mobile browser. As a result, content that conforms to this SC may not meet the BP.
- 2.4.9 Link Purpose (Link Only) at level AAA ensures compliance with this BP.
Back to Best Practices list.
[MEASURES] Do not use pixel measures and do not use absolute units in markup language attribute values and style sheet property values
WCAG 2.0 does not prohibit the use of the pixel unit of measure.
- 1.4.4 Resize text at level AA helps comply with this BP if named font sizes, em units or percentages are used.
Back to Best Practices list.
[NAVIGATION] Provide consistent navigation mechanisms
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[NON-TEXT_ALTERNATIVES] Provide a text equivalent for every non-text element
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[OBJECTS_OR_SCRIPT] Do not rely on embedded objects or script
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[PAGE_TITLE] Provide a short but descriptive page title
- 2.4.2 Page Titled at level A possibly ensures compliance with this BP. However, to comply with the BP, it may be necessary to truncate the title to meet the BP. In this case it may be useful to put the most important, differentiating information first, also helping screen reader users.
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[POP_UPS] Do not cause pop-ups or other windows to appear and do not change the current window without informing the user
- 3.2.1 On Focus at level A may possibly go some way to achieving compliance with this BP, but the SC allows popups.
- 3.2.2 On Input at level A may possibly go some way to achieving compliance with this BP, but the SC allows popups.
- 3.2.5 Change on Request at level AAA may possibly go some way toward compliance, but the SC does allow use of the
target attribute.
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[REDIRECTION] Do not use markup to redirect pages automatically. Instead, configure the server to perform redirects by means of HTTP 3xx codes
The following SCs go some way to achieving compliance with this BP. Specifically, failure F41: Failure of Success Criterion 2.2.1, 2.2.4, and 3.2.5 due to using meta refresh with a time-out ensures compliance with this BP.
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[STRUCTURE] Use features of the markup language to indicate logical document structure
The BP is less explicit about what structural elements to use, but the following SCs probably cover its intent.
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[VALID_MARKUP] Create documents that validate to published formal grammars
- 4.1.1 Parsing may go some way to complying with this BP with some of the sufficient techniques.
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