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Web Accessibility Best Practices from NASA Webmaster Community (Internal weblink)

How to perform a site assessment:

Easy, First Steps in Making a Webpage or Website Accessible:

Use a Checklist to Assess, Validate or Verify

Practical Approach to Assessing and Repairing Entire Sites

Rate sites in two stages.

Suggested list for Stage 1:

  1. ALT tags for images that are clear and informative;
  2. Use color as a subordinate element in conveying online information and navigation;
  3. Use the language identification tag in the head area of HTML documents;
  4. Convert server-side image maps to client-side image maps;
  5. Identify row and column headers on data tables (one interpretation of this guideline is that tables used for layout would not require this);
  6. Frame titling and "no frames" equivalent text;
  7. Improve content tracking as best as can done - this area includes a group of recommendations such as using consistent navigation, separating links clearly, providing jump links around link lists, etc.

Suggested list for Stage 2:

  1. Provide static pages that are regularly updated for sites that rely on dynamic delivery of information;
  2. Provide equivalent alternatives for multimedia products (closed captioning);
  3. When using Style sheets make sure the site works if the browser doesn't support Style Sheets.

Potential Metric Elements:

  1. Look at the proposed guidelines;
  2. Figure out what it would take to comply by the deadline if all possible resources were applied;
  3. Once you can quantify what it would take, you are in a position to propose what you can realistically do.

Some considerations regarding page layout

The World Wide Web Consortia Web Accessibility Guidelines recommend Style Sheets over Frames and recommend against using Tables.

The current versions of several popular Reader Software packages handle Frames quite nicely and are nearly as good at handling Tables. This is even more true when the appropriate alternate, summary and heading tags are provided.

Only one of the many current browsers (Microsoft Internet Explorer, PC/Mac) comes close to providing compliance with the current Cascading Style Sheet (CSS) specification (CSS2, also see the specification for CSS1).

This presents the following truths:

  • At least a third of all browsers in use may not support Frames.
  • Almost none of the browsers in use support Cascading Style Sheets.
  • Most of the browsers in use support Tables.
  • Probably all the sites being renovated rely to some degree on the use of Tables for layout.
  • One approach Headquarters is taking is to identify the best use of which tags will allow Tables to continue to be used as a layout tool. This is being done by first using the Bobby software and then using individuals who rely on Reader Software to access the web and determining if the site passes Bobby or not and whether the individuals using Reader Software perceive the content as it is intended. This is an iterative process and we are not yet at a point where we can report a trend or provide recommendations.

    Given the ease with which Frame pages can be accessed and the content perceived accurately by those using Reader Software, previous constraints might be reexamined on the use of Frames for sites which get heavy use by recent version browsers. Such sites would probably also be fairly simple Tables, too, though. Each approach appears to have some advantages and some disadvantages.

    Useful links relevant to site usability and accessibility

    Goddard Space Flight Center website covering the basics of web page and web site design, including rationales for favoring one type design over another;
    Links to several hundred usability sites (from usability issues, to usability design, to usability commentary);
    Links to a site which will test a page on your site for code errors, load time, popularity and more;
    Links to a site with every browser imaginable including text-only;
    Links to the Bobby utility to see if a site is "accessible";
    Links to Jakob Nielsen's Alertbox site, containing alerts covering every aspect of internet browsing;
    Links to an HTML validator operated by the World Wide Web Consortium.

  • Useful links relevant to current site design, including JavaScript & DHTML

    This site is for those who want to get into the culture of web development. Also offers opinions on hot topics by every-day developers. Covers site development and design as well with tutorials;
    This is C/NET's "" site where everything about web development from the business case to the actual design is cited;
    Similar to "" but with an even more modern, stylistically-driven, approach;
    A website which tries to be a place for new developers to get together;
    A generic help/tutorial page;
    One of many JavaScript freeware/shareware websites;
    One of many Dynamic HTML freeware/shareware websites;
    Links to IBM Guidelines for Writing Accessible Applications Using 100% Pure Java
    Links to Trace R&DCenter Information about Java Accessibility and Usability.
    Links to Macromedia’s Flash OBJECT and EMBED Tag Syntax
    Goes to the Unified Web Site Guidelines were compiled by the Trace R & D Center at the University of Wisconsin (funding from National Institute on Disability and Rehabilitation Research (NIDRR),  U.S. Dept. of Education).

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    Charles Redmond
    NASA Headquarters
    NASA Headuarters building picture Curator
    Charles Redmond
    This document last updated January 21, 2001.

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