Descrizione dell' immagine:
Image credit:
Michael Duffy, copyright© W3C.
W3C grants permission to use the image under the W3C Document License at http://www.w3.org/Consortium/Legal/copyright-documents.html.
Include a reference to the main source document, as well as credit to the graphic artist, as follows:
Image by Michael Duffy, from: Essential Components of Web Accessibility, S.L. Henry, ed. W3C (MIT, ERCIM, Keio), August 2005. http://www.w3.org/WAI/intro/components