Relationship Between
Mobile Web Best Practices 1.0 and
Web Content Accessibility Guidelines

W3C Editor's Draft 14 March 2008

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Alan Chuter (Fundación ONCE / Technosite)

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This multi-page document describes the similarities and differences between the Web Content Accessibility Guidelines (WCAG) and the Mobile Web Best Practices (MWBP).

Status of This Document

This section describes the status of this document at the time of its publication. Other documents may supersede this document. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at http://www.w3.org/TR/.

Incomplete draft: This document is an editor's copy that has no official standing and is incomplete. Particularly, the section WCAG 2.0 and MWBP Together is only an outline; WCAG 1.0 to MWBP is only partly filled out. It is subject to major changes and is therefore not intended for implementation. It is provided for review and feedback only. Please send feedback to public-bpwg-comments@w3.org (archive).

A Requirements/Analysis and changelog for Relationship Between MWBP & WCAG and a record of updates and modifications to this document are available separately.

This document was developed jointly by the Mobile Web Best Practices Working Group and the Education & Outreach Working Group (EOWG) of the Web Accessibility Initiative (WAI) as part of the Charter of the Mobile Web Best Practices Working Group (see the dependencies in the Charter).

Publication as a Working Draft does not imply endorsement by the W3C Membership. This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress. The Working Group is particularly seeking feedback on references to similar works and content to fill the remaining sections.

This document is a First Public Working Draft intended to be eventually published as a Group Note.

This document was produced by groups operating under the 5 February 2004 W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the Mobile Web Best Practices Group and also maintains a public list of any patent disclosures made in connection with the deliverables of the Education and Outreach Working Group; those pages also include instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.

Longevity and Versioning

This document makes primary reference to Web Content Accessibility Guidelines (WCAG) 1.0 and the 11 December 2007 draft of WCAG 2.0 and Mobile Web Best Practices 1.0. New versions of these documents are expected to be produced during the life of this document. New versions of this document should be produced as soon as new versions of the referenced Recommendations are published and well understood.


Readers of this document are expected to be familiar with the creation of Web sites, and to have a general familiarity with the technologies involved, such as Web servers and HTTP. Readers are not expected to have a background in mobile-specific technologies. it is important to understand the other W3C Recommendations to which it refers (see Related Documents of Interest).

Our intention is to make it clear to all involved what the Best Practices are, and hence establish a common basis of understanding. As a result of wishing to be clear to those not already involved in the development of mobile friendly content, some of our statements may appear to be obvious or trivial to those with experience in this area.

The document is not targeted solely at developers; others, such as interaction and graphic designers are encouraged to read it.

Many readers of the document are likely to have a good knowledge of general Web accessibility but are concerned with the problems of persons with disabilities in the mobile context.


This document describes the relationships, overlaps and differences between MWBP and WCAG. This document does not create any further requirements beyond those defined in the MWBP and the WCAG.

Web accessibility for people with disabilities is beyond the scope of this document except where it especially affects mobile users. It is described in WCAG. The needs of users in the mobile Web context is beyond the scope of this document except where it especially affects users with disabilities. It is described in MWBP.

Table of Contents

How to Use This Document

Before continuing with this document further you may wish to read the introductory documents that accompany it:

This overview introduces a multi-page document describing the relationship between WCAG and MWBP. There are five other sections (each a separate page) corresponding to the relationships between MWBP 1.0 and two versions of WCAG. Of the other five, you may prefer to concentrate on only one, either to address both accessibility or mobile-awareness together, or if you currently focus on one, the aspect towards which you are aiming:

Some apparently common terms (such as “partially”, “possibly”, “everything”, “nothing”) are used with precise meanings in this document, as defined in “Special Meanings of Terms Used in this Document.”

The Problem of Multiple Overlapping Requirements

Certain features of Web content cause barriers both for users of mobile devices and users with disabilities. However, the ways to overcome these barriers are dealt with in different documents, depending on the category of users who the document seeks to help. While reading this section it can be useful to compare the effects that content features have on different users. This is described in the separate document Experiences Shared by People with Disabilities and by People Using Mobile Devices [Editors' Draft, January 2008]

Many Web sites have already adopted the WCAG, which explains how to make Web content accessible to people with disabilities. In many countries compliance with WCAG is mandatory. The MWBP document specifies Best Practices for delivering Web content to mobile devices. The principal objective is to improve the user experience of the Web when accessed from such devices.

Increasingly, web content is designed to comply with one of these sets of guidelines or best practices. However, misunderstanding of their requirements and the assumptions about the user and device characteristics on which they are based, leads to less than optimal implementation. This document is intended to serve as an added justification or argument for aiming for compliance with either of the recommendations. The benefits include:

It may be useful for building the business case for adopting either WCAG or MWBP in a web site that already complies with one, or for adopting both together. For accessibility, the Web Accessibility Initiative provides a guidance document Developing a Web Accessibility Business Case for Your Organization.

Separation of Concerns

Accessibility specialists are not generally concerned with the mobile context. Likewise Mobile Web specialists tend not to be concerned with accessibility for persons with disabilities. However they do have common requirements and design principles.


Unlike the Web Content Accessibility Guidelines, the Mobile Web Best Practices are not prioritized. MWBP relate to checkpoints of all the WCAG 1.0 priorities (1, 2 and 3).

Why No WCAG to MWBP Mapping Table?

While there appear to be many similarities between many of the WCAG provisions and those of the Mobile Web Best Practices, in reality there are many subtle differences. A simple table would be misleading and lead to duplication of work in some aspects and and inadequate implementations in others. Also the relationships are not symmetrical (SC x relates to BP y, but it does not follow therefore that BP y relates to SC x). For example, while both WCAG and MWBP require good colour contrast, WCAG emphasises users' color perception while MWBP focuses on the device characteristics (reduced color palette, poor lighting). This means that complying with WCAG may meet the related MWBP, but not the inverse.

Readers familiar with accessibility and WCAG can not be expected to be aware of the mobile web, mobile devices, infrastructure and the MWBPs. Similarly, Mobile Web specialists can not be expected to have a thorough knowledge of the needs of users with disabilities and assistive technology. More information and guidance is needed.

Testing with Users and Devices

Both MWBP and WCAG provide information about the possible barriers to users, and advice about how to avoid them. Compliance does not guarantee usability or accessibility. Barriers may arise other than those described and content providers should avoid them by performing user testing. Other solutions than those described may be found to the barriers. User testing should always include a representative range of users, including those with different disabilities, as well as devices.

Comment: Cite the relevant text from each recommendation that advises doing user testing. Does WCAG 2.0 recommend testing with users?

Special Meanings of Terms Used in this Document

Some common words are used in this document with specific meanings. These are defined below.

Concerning the effort required to meet a checkpoint or best practice, this means that the other provisions do not cover this aspect at all, and it is necessary to comply with these checkpoints from scratch. As there is no coverage in the MWBPs, no BPs are referenced, or vice versa.
Concerning the effort required to meet a checkpoint or best practice, this means that content already complies with this provision so no further effort is necessary.
no added benefit
Indicates a provision of a recommendation that has no specific additional benefit for users covered by the other recommendation beyond that experienced by the general user. This does not imply that the other user group will not benefit, but rather that they will not dereive any extra benefit. For example, since users with disabilities use the Web on mobile devices they are expected to benefit from the MWBP like any other user. However some BPs may bring added benefits to users with disabilities beyond the benefit to the general mobile user. If not, the term “no added benefit” is used.
In many cases there is no direct correspondence between one provision and another. In some cases the scope may be different, giving partial compliance. For example, the NON-TEXT_ALTERNATIVES best practice covers images, but the scope of the WCAG provisions is much wider. In these cases the word “partially” is used.
In many cases 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. For example, [COLOR_CONTRAST] is intended to help mobile users with monochrome displays or in poor lighting conditions. By also considering the needs of users with color deficits (color blindness) the same BP makes content accessible to more users and ensures compliance with success criterion 1.4.3 “Contrast (Minimum)”. In these cases, the word “possibly” is used.
Concerning the effort required to meet a checkpoint or best practice, this means that more effort of some kind is necessary to comply with the provision. What is required depends on the individual checkpointor best practice. For each there is a list of the provisions that provide partial compliance or are in some way related.