PAS 78-2006 Guide to good practice in commissioning accessible websites《可登录网站调试的良好规范指南》.pdf

1、PUBLICLY AVAILABLE SPECIFICATIONPAS 78:2006Guide to good practice in commissioning accessible websitesICS 35.240.30Licensed Copy: Wang Bin, na, Fri May 12 03:05:02 BST 2006, Uncontrolled Copy, (c) BSIPAS 78:2006This Publicly Available Specification comes into effect on 8 March 2006 BSI 8 March 2006I

2、SBN 0 580 46567 5Amendments issued since publicationAmd. No. Date CommentsLicensed Copy: Wang Bin, na, Fri May 12 03:05:02 BST 2006, Uncontrolled Copy, (c) BSIPAS 78:2006 BSI 8 March 2006iContentsPageForeword iiIntroduction 11Scope 52 Normative references 53 Terms and definitions 54 General principl

3、es 114.1 Development of an accessibility policy 114.2 Upholding W3C guidelines and specifications 114.2.1 General 114.2.2 Content formats 114.2.3 Authoring tools 114.3 Conformance checking 124.4 Involving disabled people in the requirements gathering and conceptual design process 124.5 Regular testi

4、ng by disabled people 124.6 Additional accessibility provisions 125 How disabled people use websites 135.1 General 135.2 Operating systems 135.3 Access technology and other considerations for blind and partially sighted people 145.4 Access technology and other considerations for deaf and hard of hea

5、ring people 155.5 Access technology and other considerations for people with learning disabilities 155.6 Access technology and other considerations for people with cognitive impairments (eg dyslexia) 165.7 Access technology and other considerations for people with motor impairments 166 Defining the

6、accessibility policy for the website 176.1 General 176.2 Content of the accessibility policy 176.3 Publicly available accessibility policy statement 196.4 Accessibility guidelines 19Licensed Copy: Wang Bin, na, Fri May 12 03:05:02 BST 2006, Uncontrolled Copy, (c) BSIPAS 78:2006ii BSI 8 March 20067 W

7、eb technologies 217.1 Common web technologies 217.2 Structural languages 227.3 Style sheets eg CSS 227.4 Client side scripting and programming languages eg JavaScript and Java 237.4.1 Object models 237.5 Plug-in rich media formats 237.5.1 General 237.5.2 Portable Document Format (PDF) 247.5.3 Flash

8、247.5.4 Audio-video content 257.6 Visual-orientated anti-robot tests 268 Accessibility testing and maintenance 268.1 General 268.2 Creating a test plan 288.3 Determining technical accessibility 288.3.1 Automated testing 288.3.2 Validation 298.3.3 Testing with assistive technology 298.4 Determining u

9、sable accessibility 298.4.1 Expert review 308.4.2 Conformance inspection 308.4.3 User testing 318.4.3.1 Why is user testing necessary? 318.4.3.2 User testing methods 318.4.3.3 Budgetary considerations 328.4.3.3.1 Sample sizes 328.4.3.3.2 User recruitment 328.4.3.3.3 Using specialized evaluators 328.

10、5 Maintaining accessibility 339 Contracting web design and accessibility auditing services 349.1 Choosing a website developer 349.2 Agencies providing web accessibility consultancy 35Licensed Copy: Wang Bin, na, Fri May 12 03:05:02 BST 2006, Uncontrolled Copy, (c) BSIPAS 78:2006 BSI 8 March 2006iiiA

11、nnex A (informative) Suggested user profiles include: 36Annex B (informative) Possible criteria for determining success 37Annex C (informative) Suggested questions for suppliers 38Annex D (informative) Accreditation 40Annex E (informative) Various references 41Annex F (informative) Contracting usabi

12、lity testing services 44Annex G (informative) How to select a CMS system 45Bibliography 47Standards 56Useful websites 56Relevant publications 57Index 50Licensed Copy: Wang Bin, na, Fri May 12 03:05:02 BST 2006, Uncontrolled Copy, (c) BSIPAS 78:2006iv BSI 8 March 2006ForewordThis Publicly Available S

13、pecification (PAS) has been developed by the Disability Rights Commission (DRC) in collaboration with the British Standards Institution (BSI). No copying without permission of BSI except as permitted by copyright law. Acknowledgement is given to the following organizations that were consulted in the

14、 development of this specification.AbilitynetBritish Broadcasting Corporation (BBC)Cabinet Office (e-Government Unit)Cxpartners (representing the Usability Professionals Association)IBMRNIB (Royal National Institute of the Blind)TUniversity College LondonUsability Professionals Association (UPA)Wide

15、r comments from other interested parties were invited by BSI. The expert contributions made by the organizations and individuals consulted in the development of this Publicly Available Specification are gratefully acknowledged.Please note that during the production of this PAS Macromedia was bought

16、by Adobe and all resources regarding Flash accessibility will eventually be available at .This Publicly Available Specification does not replace, contradict or supplement any of the World Wide Web Consortium (W3C) guidelines or specifications. This PAS is vendor neutral and product neutral. Generic

17、terms are used in preference to brand names to ensure impartiality.Licensed Copy: Wang Bin, na, Fri May 12 03:05:02 BST 2006, Uncontrolled Copy, (c) BSIPAS 78:2006 BSI 8 March 2006vSummary of pagesThis document comprises a front cover, an inside front cover, pages i to v, a blank page, pages 1 to 56

18、, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. This Publicly Available Specification does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Th

19、is Publicly Available Specification has been prepared and published by BSI, which retains its ownership and copyright. BSI reserves the right to withdraw or amend this Publicly Available Specification on receipt of authoritative advice that it is appropriate to do so. This Publicly Available Specifi

20、cation will be reviewed at intervals not exceeding two years, and any amendments arising from the review will be published as an amended Publicly Available Specification and publicised in Update Standards.Compliance with this Publicly Available Specification does not of itself confer immunity from l

21、egal obligations.This Publicly Available Specification is not to be regarded as a British Standard.Licensed Copy: Wang Bin, na, Fri May 12 03:05:02 BST 2006, Uncontrolled Copy, (c) BSIblankLicensed Copy: Wang Bin, na, Fri May 12 03:05:02 BST 2006, Uncontrolled Copy, (c) BSIPAS 78:2006 BSI 8 March 20

22、06 1IntroductionWhy make your website accessible to disabled people?The introduction of the Disability Discrimination Act 1995 (DDA) 1 is only one reason why it is in the interest of website commissioners to develop accessible websites. Accessible websites also have the potential to widen a websites

23、 current audience and reach new ones: The Family Resources Survey 2 found that there are almost 10 million disabled people in the UK with a combined spending power in the region of 80 billion pounds per annum. Furthermore there are millions of other individuals that are affected by sensory, physical

24、 and/or cognitive impairments, including those resulting from the ageing process. Research undertaken by the DRC “The Web: Access and inclusion for disabled people” 3 has confirmed that people without disabilities are also able to use websites that are optimized for accessibility more effectively an

25、d more successfully. Content developed upholding World Wide Web Consortium (W3C) guidelines and specifications can be more easily transferred to other media, such as interactive TV, mobile phones and handheld computers. Accessible content, for example where a text equivalent is provided for graphica

26、l elements, is highly visible to search engines, often leading to higher rankings.Ensuring accessibility can also be a source of good publicity, as social inclusion results in a fairer world with equality of opportunity. Further business benefits achieved by making websites accessible are given at h

27、ttp:/www.w3.org/WAI/bcase/benefits.html.The main focus of this document is the commissioning of public-facing (internet) websites but the principles can also be used by commissioners of intranet or extranet websites.It is important to note that not all web developers will have practical accessibilit

28、y design experience and/or accessibility expertise; see Clause 9 for advice on how to find suitable web developers.Licensed Copy: Wang Bin, na, Fri May 12 03:05:02 BST 2006, Uncontrolled Copy, (c) BSIPAS 78:20062 BSI 8 March 2006The Disability Discrimination Act 1995 (DDA)The DDA and the secondary l

29、egislation applied within Northern Ireland have placed a legal duty on service providers to make reasonable adjustments to the way they provide services to ensure that disabled people can use them. The DDA states that disabled people should not be treated less favourably than other people when acces

30、sing services. This duty extends to the provision of websites where a website falls within the definition of a service under the terms of the DDA. For the purposes of this document, website commissioners are assumed to have responsibility for this duty.It is not possible to provide a definitive spec

31、ification for a fully accessible website which will satisfy the requirements of the DDA, however the guidance set out in this Publicly Available Specification represents what the Disability Rights Commission (DRC) believes to be good practice.The Disability Rights Commission (DRC)The DRC is an indep

32、endent body established in April 2000 by an Act of Parliament to stop discrimination and promote equality of opportunity for disabled people. The DRCs goal is “a society where all disabled people can participate fully as equal citizens”.In 2002, the DRC published a Code of Practice entitled “Rights

33、of Access Goods, Facilities, Services and Premises” 4 to accompany Part 3 of the DDA. The Code makes explicit reference to websites as “services” in accordance with the DDAs definition of the term. At the time of publication the DRC were updating the Part 3 Code of Practice.The DRC Formal Investigat

34、ion into website accessibilityIn April 2004, the DRC published the report of their Formal Investigation into web accessibility in the UK. One significant finding was that 81 per cent of websites surveyed failed to uphold the most basic W3C accessibility guidelines and specifications, even though man

35、y website commissioners and developers claimed to be aware of the importance of making websites accessible.Licensed Copy: Wang Bin, na, Fri May 12 03:05:02 BST 2006, Uncontrolled Copy, (c) BSIPAS 78:2006 BSI 8 March 2006 3The DRC has concluded that there is a need for best practice guidance on the p

36、rocess of commissioning accessible websites. This Publicly Available Specification has been commissioned to provide guidance to website commissioners on: the steps that should be taken to commission accessible websites the W3C guidelines and specifications to be adopted the role of the guidelines an

37、d specifications, software tools and user testing within the development life cycle. Another important finding of the Formal Investigation involved accessibility testing. All the websites surveyed were tested using automated conformance testing tools (see 3.5); however subsequent user testing with d

38、isabled participants uncovered further instances where websites did not uphold the W3C guidelines and specifications. Therefore it can be concluded that automated testing alone cannot provide a complete testing solution.Ensuring accessibilityThe web will only be truly accessible when all of the foll

39、owing work in harmony, using the relevant W3C guidelines and specifications: website developers ensure that their web content upholds W3Cs Web Content Accessibility Guidelines (WCAG) (see 3.22) website developers ensure that any non-W3C formats used on the website incorporate accessible design eleme

40、nts or follow accessible design guidelines applicable to that format authoring tool developers ensure that their products produce web content that upholds WCAG browser developers ensure that their products uphold W3Cs User Agent Accessibility Guidelines (UAAG) operating system (OS) developers provid

41、e accessibility features within their operating system, and work with access technology developers to ensure their products work in harmonyLicensed Copy: Wang Bin, na, Fri May 12 03:05:02 BST 2006, Uncontrolled Copy, (c) BSIPAS 78:20064 BSI 8 March 2006 software developers, disability advocacy group

42、s (such as AbilityNet, RNIB (Royal National Institute of the Blind) and public sector organizations (such as BBC and the Government) provide advice to disabled people on how to optimize their computer setup educators and training organizations that provide training on web design include accessible w

43、eb design in the curriculum of design courses.The DRC recommends a combined approach to accessibility testing, including as essential requirements: the application of W3C guidelines and specifications (in particular WCAG) testing conformance to guidelines and specifications (in particular WCAG, see

44、Clause 8) user testing with potential users, including disabled users (see Clause 8), during the design and development stages of the website development.Summary for commissioning an accessible websitea) Consider what the site should do and for whom: write the accessibility policy/specification (see

45、 Clause 6).b) Consider who is going to create it, and how accessibility can be assured: investigate the reputation of those designing and developing the site and the guidelines/processes they uphold (see Annex C).c) Consider how the web developers are going to create and maintain the website: invest

46、igate whether the website will be created and maintained manually, using a CMS, or by using an automated web application (see 6.5.3) ensure that a plan is in place to maintain levels of accessibility during the website lifecycle (see 8.5).d) Consider how accessibility will be tested (see Clause 8).L

47、icensed Copy: Wang Bin, na, Fri May 12 03:05:02 BST 2006, Uncontrolled Copy, (c) BSIPAS 78:2006 BSI 8 March 2006 51 ScopeThis Publicly Available Specification outlines good practice in commissioning websites that are accessible to and usable by disabled people.It gives recommendations for: the manag

48、ement of the process of, and guidance on, upholding existing W3C guidelines and specifications; involving disabled people in the development process and using the current software-based compliance testing tools that can assist with this.It is applicable to all public and private organizations that w

49、ish to observe good practice under the existing voluntary guidelines and the relevant legislation on this subject and is intended for use by those responsible for commissioning public-facing websites and web-based services.2 Normative referencesThe following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies.W3C guidelines and specifications available at http:/www.w3.org/3 Terms and definitions3.1 acce