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<long-desc> Long Description

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

Usage/Remarks

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.
Attributes
content-type
specific-use

Base Attributes

id
xml:base
xml:lang

Linking Attributes

xlink:actuate
xlink:href
xlink:role
xlink:show
xlink:title
xlink:type (fixed value = simple)

Namespaces

xmlns:xlink (fixed value = http://www.w3.org/1999/xlink)
Models and Context
May be contained in
<array>, <chem-struct>, <chem-struct-wrap>, <code>, <disp-formula>, <disp-formula-group>, <fig>, <fig-group>, <graphic>, <inline-graphic>, <inline-supplementary-material>, <media>, <preformat>, <supplementary-material>, <table-wrap>, <table-wrap-group>
Description
Text, numbers, or special characters, zero or more
Content Model
<!ELEMENT  long-desc    (#PCDATA %long-desc-elements;)*              >
Expanded Content Model

(#PCDATA)*

Tagged Sample

Figure description

...
<fig>
 <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>
</fig>
...
Related Resources