Empty Elements
Some elements do not have any content at all. These are
called empty elements and are sometimes written
with a closing />
. For
example:
<image source="bus.jpg" width="152" height="345" alt="Alan Turing standing in front of a bus" />
These elements are declared by using the keyword EMPTY
for the content specification. For
example:
<!ELEMENT image EMPTY>
This merely says that the image
element must be empty, not that it
must be written with an empty-element tag. Given this declaration,
this is also a valid image
element:
<image source="bus.jpg" width="152" height="345" alt="Alan Turing standing in front of a bus"></image>
If an element is empty, then it can contain nothing, not even
whitespace. For instance, this is an invalid image
element:
<image source="bus.jpg" width="152" height="345" alt="Alan Turing standing in front of a bus"> </image>
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