2. Information which is indicated by color
It must be sure that information which are indicated by color are also given by text.
For example the availability of a product in an online shop.
The green rectangles in shows you, the product is available.
To make it more accessible an alternative to the information given by color should be available. This could be invisible by using the alt
attribute of the img element, or visible by a text note near by the rectangles.
This example should give a small impression which problems blind or generally physically handicapped people got with unstructured information on websites.
A Checklist for website development is offered by the W3 - Consortium on the page:
[Example 1: Description of Pictures] [Example 2: Information indicated by color]
[Example 3: Usage of Scripts] [WAI Startpage]