The header() method is used to output the XML declaration.

<?php
echo $xml->header(); 
// generates: <?xml version="1.0" encoding="UTF-8" ?>
?>

1. <?php
2. echo $xml->header();
3. // generates: <?xml version="1.0" encoding="UTF-8" ?>
4. ?>

You can pass in a different version number and encoding type as parameters of the header method.

<?php
echo $xml->header(array('version'=>'1.1')); 
// generates: <?xml version="1.1" encoding="UTF-8" ?>
?>

1. <?php
2. echo $xml->header(array('version'=>'1.1'));
3. // generates: <?xml version="1.1" encoding="UTF-8" ?>
4. ?>