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Information Technology Systems and Services

How to Write Long Text Alternatives

As Joe Clark wrote in his classic book Building Accessible Websites:

It would not be remiss to hope that a long description conjures an image - the image - in the mind's eye, an analogy that holds true even for the totally blind.

To write a long text description ask yourself, if there is no description, what will the user miss?

Long Text Alternatives Good Practices

For further details consult the National Center for Accessible Media's Effective Practices for Description of Science Content within Digital Talking Books.

A link below or near an image may be used to provide a long description within the document itself or to link to a separate page. This is simple method as everyone will have access to the it.

Linking to separate document can also provide efficiency and scalability making authoring and maintenance easy wherever instances of the same image are used in multiple locations. It is analogous to the power of external style sheets.

One external file provides and controls the description for multiple docs.


Using on Page Description with Location Info in the alt Attribute

When a long description is provided on the same web page as an image, its location can be described using the alt attribute of the image. The location information needs to be clear and accurate to help users locate the content. The syntax is:

  alt="Number of subscribers. Described under the
  heading: 'Graph Description: Subscriber Increase'"
  <h4>Graph Description: Subscriber Increase</h4>

Other Methods

The W3C provides more options for providing long descriptions.