Guidelines for creating accessible web sites are produced by the governments of differ-
ent countries and non-government organisations such as charities. Internet standards
organisations such as the World Wide Web Consortium have been active in promoting
guidelines for web accessibility through the Website Accessibility Initiative (see
http://www.w3.org/WAI). This describes common accessibility problems such as:images without alternative text; lack of alternative text for imagemap hot-spots; misleading
use of structural elements on pages; uncaptioned audio or undescribed video; lack of
alternative information for users who cannot access frames or scripts; tables that are diffi-
cult to decipher when linearized; or sites with poor color contrast.A fuller checklist for acessibility compliance for web site design and coding using
HTML is available from the World Wide Web Consortium (www.w3.org/TR/WCAG10/
full-checklist.html).
There are three different priority levels which it describes as follows:- Priority 1 (Level A). A web content developer must satisfy this checkpoint. Otherwise,
one or more groups will find it impossible to access information in the document.
Satisfying this checkpoint is a basic requirement for some groups to be able to use
web documents. - Priority 2 (Level AA). A web content developer should satisfy this checkpoint.
Otherwise, one or more groups will find it difficult to access information in the docu-
ment. Satisfying this checkpoint will remove significant barriers to accessing web
documents. - Priority 3 (Level AAA). A web content developer may address this checkpoint.
Otherwise, one or more groups will find it somewhat difficult to access information
in the document. Satisfying this checkpoint will improve access to web documents.
RESEARCHING SITE USERS’ REQUIREMENTSActivity 7.2 Allowing for the range in access devices
One of the benefits of accessibility requirements is that they help web site owners and web
agencies consider the variation in platforms used to access web sites.Questions
1 Update the compilation in Table 7.4 to the latest values using Onestat.com or other data
from web analytics providers.
2 Explain the variations. Which browsers and screen resolutions do you think should be
supported?Table 7.4 Summarises the range in browsers and screen resolutions used at the
time of writingWeb browser popularity Screen resolution popularity
1 Microsoft IE 86.63 % 1 1024 768 57.38%
2 Mozilla Firefox 8.69 % 2 800 600 18.23%
3 Apple Safari 1.26 % 3 1280 1024 14.18%
4 Netscape 1.08 % 4 1152 864 4.95%
5 Opera 1.03 % 5 1600 1200 1.67%
Source: Onestat press releases (www.onestat.com)INMA_C07.QXD 17/5/06 4:23 pm Page 315