Abstract
This technical report describes the relationships, overlaps and differences between the Web Content Accessibility Guidelines (WCAG) and the Mobile Web Best Practices (MWBP). Introductory information can be found in Web Content Accessibility and Mobile Web: Making a Web Site Accessible Both for People with Disabilities and for Mobile Devices.
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/.
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).
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.
Please send comments on this document to public-bpwg-comments@w3.org (with public archive).
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.
Changes since the last version of this document are described in the changelog of updates and modifications, available separately. Comments on this new version are welcome.
How to Use This Document
Before continuing with this document, please read the introductory documents: Web Content Accessibility and Mobile Web: Making a Web Site Accessible Both for People with Disabilities and for Mobile Devices and Experiences Shared by People with Disabilities and by People Using Mobile Devices.
This technical report includes five subpages that describe the relationship between each version of WCAG and MWBP 1.0. Each page covers a different scenario based on which document you are starting from, as listed [in the table] below.
REVIEW NOTE: Do you find the bulleted list or the table easier to understand?
- If you have done MWBP 1.0 and are considering progressing to:
- If you have done WCAG 1.0 and considering progressing to MWBP 1.0, then read WCAG 2.0 to MWBP
- If you have done WCAG 2.0, and considering progressing to MWBP 1.0, then read WCAG 1.0 to MWBP
Scope
This technical report is created as a supporting document to WCAG and MWBP, and does not replace either of those. For further and comprehensive information about how to make Web content accessible to people with disabilities, please refer to the Web Content Accessibility Guidelines. Similarly, for further and comprehensive information about best Practices for delivering Web content to mobile devices, please refer to the Mobile Web Best Practices.
Managing Overlapping Requirements
As explained in the document Experiences Shared by People with Disabilities and by People Using Mobile Devices [Editors' Draft, January 2008], certain features of Web content can cause barriers to both people with disabilities (using desktop or laptop computers) and people without disabilities who are using mobile devices. Although W3C provides best practices and guidelines to address such barriers, depending on the user group these barriers are addressed in different documents. However, considering overlapping requirements has some benefits which include:
- Unnecessary effort and cost is often expended in complying with recommendations separately or consecutively. This document explains the overlaps between the two recommendations, allowing for greater efficiency.
- Content providers may decide not to adopt another recommendation due to imagined cost. This document explains the overlaps and synergies between the two recommendations, and the ways in which once one recommendation is adopted, the other is less onerous.
- Specialists in the “Web accessibility” or “mobile Web” fields may be unaware of the importance of the other and have difficulty communicating. This document can spread awareness and improve communication by helping specialists in different fields understand that their concerns are often related and parallel. It should help trainers teaching students already experienced in another field using terminology and concepts they are familiar with and without repeating material they already know.
- Vendors of evaluation tools may expend unnecessary effort and cost developing test implementations that already exist for the other recommendation. The information in this document allows them to understand how implementations may be reused or easily adapted.
Priorities and Levels
The Mobile Web Best Practices (BP) are not assigned levels. MWBP relates to checkpoints of all the WCAG 1.0 priorities (1, 2 and 3) and to all the WCAG 2.0 level A, AA and AAA success criteria.
Why No Mapping Table?
While there appears to be many similarities between many of the WCAG provisions and those of the MWBPs, there are still many subtle differences. A simple table would be misleading and lead to duplication of work in some aspects 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.
Web Content Accessibility Guidelines 2.0 and
Mobile Web Best Practices 1.0 Together
As described in this document, the two recommendations are complementary. The motivation for adopting them may be different for each (for example, commercial, regulatory, altruistic). It has been described elsewhere that retrofitting existing websites for compliance with another set of non-functional requirements is much more costly than complying during the design and development phases. The cost of late implementation (content repair, staff training, redesigning workflow) seperately may also be much greater than doing both together, due to the synergies between them. (So we suggest that for many projects there are compelling reasons to do both at the same time...)
The document Experiences Shared by People with Disabilities and by People Using Mobile Devices shows some of the overlaps between the Recommendations from the users' standpoint.
This document looks at ways in which some of the Mobile Web BPs and WCAG SCs can be addressed together. Future versions of this document may provide detailed guidance on how to approach both Recommendations together. This version provides just a brief outline of how it is possible to devise a coherent set of requirements for a given project covering both recommendations together. It is important to understand that WCAG 2.0 success criteria (SCs) are assigned levels, and for this reason compilation of the list of requirements begins with WCAG. The following steps can be used to draw up a list of requirements:
- Decide on the WCAG level required for the project and compile a list of the SC that it must meet.
- Compare with the list of MWBPs
- Using the document 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, identify which MWBPs overlap (completely or partially) with the applicable SCs and those that must be considered alone.
For the latest version of any W3C specification please consult the list of W3C Technical Reports.
- [WAI/Experiences]
- Experiences Shared by People with Disabilities and by People Using Mobile Devices
- [WAI/Mobile]
- Web Content Accessibility and Mobile Web: Making a Web Site Accessible Both for People with Disabilities and for Mobile Devices
- [MWBP1.0]
- Mobile Web Best Practices 1.0, Rabin, J. and McCathieNevile, C., November 2006 (see http://www.w3.org/TR/mobile-bp/)
- [WCAG1.0]
- Web Content Accessibility Guidelines 1.0, W. Chisholm, G. Vanderheiden and I. Jacobs, May 1999 (see http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505/)
- [WCAG2.0]
- Web Content Accessibility Guidelines 2.0, B. Caldwell, M. Cooper, L. Guarino Reid and G. Vanderheiden (see http://www.w3.org/TR/WCAG20)
Appendix B: Special Terms
Some common words are used in this document with specific meanings. These are defined below.
- nothing
- 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.
- partially
- 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.
- possibly
- 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.
- something
- 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.
Appendix C: Acknowledgements
The editor acknowledges the contributions of members of the WAI Education & Outreach Working Group and the Mobile Web Best Practices Working Group in compiling this document, in particular Charles McCathieNevile (Opera Software).