Processing instructions (PIs) enable you to provide information
to the application that uses the processed XML. Processing instructions
are enclosed in <? and ?> delimiters
and must have a name, called the target, followed by optional data
that is processed by the application that uses the XML. Each application
that uses the XML must process the targets that it recognizes and ignore
any other targets.
The XML declaration at
the beginning of an XML document is an example of a processing instruction.
You cannot use the string xml as
the name of any other processing instruction target.
In this example, usething is
the name of the target, and thing=this.thing is
the data to be processed by the receiving application:
<?usething thing=this.thing?>
