Long Description

Full description or summary of the content of an object such as a graphic, table, figure, or text box.


The long description is a non-visual element used by systems such as pronouncing screen readers to make the object accessible to people or systems that cannot read/see/display the object.
Long Description Contents: This element was originally designed to contain a description, but some newer systems expect this element to contain a URI that points to such a description. Best Practice is to incorporate a textual description, including or ending with an untagged URI, and repeat the URI in the @xlink:href attribute so that a link can be made.
Accessibility: Please reserve this tag for accessibility uses such as pronouncing screen readers. The <long-desc> is not a visual element; rather, its purpose is to be spoken in circumstances where the visual form of the object cannot be viewed. This element differs from the <alt-text> element in both length and purpose. The <alt-text> is typically very short, for quick scan reading by a screen reader or showing as words behind a graphic. The <long-desc> is meant for an extended description of an object such as a figure, table, graphic, etc., for example, a textual summary of a pie chart that explains both the visual form of the chart and significance of its findings.
Best Practice: The <long-desc> element should not to be used as a replacement for <caption>, which is a visual element typically displayed alongside a figure, table, etc. Thus <long-desc> should not be used to hold supplementary data. The <long-desc> is not a visual element.

Related Elements

The similar non-visual element <alt-text> typically contains a very short phrase. The element <long-desc> either contains or points to an extended description.


Model Description

Text, numbers, or special characters, zero or more

This element may be contained in:


 <caption><title>Truth Table</title></caption>
 <alt-text>Truth Table: NOR Gate</alt-text>
 <long-desc>Truth table showing that the output of a NOR gate is zero 
  if any of the input is 1 and the output is 1 only if both the inputs 
  of the gate is 0.</long-desc>
 <graphic xlink:href="flip-flop-NOR-gate.jpg"></graphic>