Source
File: wp-includes/functions.php
function _xml_wp_die_handler( $message, $title = '', $args = array() ) {
list( $message, $title, $parsed_args ) = _wp_die_process_input( $message, $title, $args );
$message = htmlspecialchars( $message );
$title = htmlspecialchars( $title );
$xml = <<<EOD
<error>
<code>{$parsed_args['code']}</code>
<title><![CDATA[{$title}]]></title>
<message><![CDATA[{$message}]]></message>
<data>
<status>{$parsed_args['response']}</status>
</data>
</error>
EOD;
if ( ! headers_sent() ) {
header( "Content-Type: text/xml; charset={$parsed_args['charset']}" );
if ( null !== $parsed_args['response'] ) {
status_header( $parsed_args['response'] );
}
nocache_headers();
}
echo $xml;
if ( $parsed_args['exit'] ) {
die();
}
}