Php <<< operator

<?php

// IE - 200 OK
// Chrome - text/plain, 200 OK
// FF - application/rss+xml, 200 OK
header("Content-Type: application/rss+xml");  

// IE - 200 Ok
// Chrome - application/rss+xml, 200 OK
// FF - text/html, 200 OK
//header("Content-Type: text/xml");

// be careful with the end 'RSS;', or will get 500 Error
// 1. no space before or after it, like ' RSS;' or 'RSS;    '
// 2. must add a new line after it

echo $xmlstr = <<<RSS
<?xml version="1.0"?>
<rss version="2.0" xmlns:media="http://search.yahoo.com/mrss/"> 
    <channel>
        <title>x</title>
        <link>x</link>
        <description>x</description>
        <language>x</language>
        <copyright>x</copyright>
        <generator>x</generator>
        <managingEditor>x</managingEditor>
        <webMaster>x</webMaster>
        <ttl>0</ttl>

        <item>
            <title>Bringing Cutting-Edge Skills to Philippines Public Schools</title>
            <link>http://www.austraining.com.au/newsandstories/120</link>
            <description>Imagine teaching a computer class with fifty-five (55) students sharing about ten almost obsolete computers. While to others this herculean task might sound impossible, this is a usual daily routine for Anwar, a high school teacher in a public school nestled in a disadvantaged community in southern Philippines.</description>
            <pubDate>Thu, 10 Jun 2010 12:00:00 GMT</pubDate>
            <media:thumbnail url="http://www.xxx.com.au/rssfeeds/attachments/view/anwar.jpg" width="144" height="108" time="16:37:27" />
        </item>
    </channel>
</rss>
RSS;
// there must be a new line after it, can't delete this line