What are the best practices for incorporating PHP code within an XML file to ensure proper output?

When incorporating PHP code within an XML file, it is important to ensure that the PHP code is properly enclosed within CDATA sections to prevent parsing errors. This can be achieved by using the `<![CDATA[ ... ]]>` syntax to encapsulate the PHP code. Additionally, it is crucial to escape any special characters within the PHP code to maintain the validity of the XML structure. ```xml <example> <data><![CDATA[<?php echo "Hello, World!"; ?>]]></data> </example> ```