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XML is a standard for
markup-based structured documents. Here is an example XML
document:
<?xml version="1.0"?>
<EXAMPLE prop1="gnome is great" prop2="& linux too">
<head>
<title>Welcome to Gnome</title>
</head>
<chapter>
<title>The Linux adventure</title>
<p>bla bla bla ...</p>
<image href="linus.gif"/>
<p>...</p>
</chapter>
</EXAMPLE>
The first line specifies that it's an XML document and gives useful
information about its encoding. Then the document is a text format whose
structure is specified by tags between brackets. Each tag opened has
to be closed. XML is pedantic about this. However, if a tag is empty
(no content), a single tag can serve as both the opening and closing tag if
it ends with /> rather than with >. Note
that, for example, the image tag has no content (just an attribute) and is
closed by ending the tag with />.
XML can be applied sucessfully to a wide range of uses, from long term
structured document maintenance (where it follows the steps of SGML) to
simple data encoding mechanisms like configuration file formatting (glade),
spreadsheets (gnumeric), or even shorter lived documents such as WebDAV where
it is used to encode remote calls between a client and a server.
Daniel Veillard
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