php输出xml格式字符串(用的这个)

<?php
header("Content-type:text/xml;charset=utf-8");
$aaa =<<<html
<?xml version='1.0' encoding='utf-8'?>
<SubFucParams>
<Version>1.0.0.0</Version>
<Publisher>d3e59f1d78f344c682bef3517a4b667f</Publisher>
<PublisherName>rong</PublisherName>
<Story>
<Type>.txt</Type>
<Title>
<MainTitle>www</MainTitle>
</Title>
<Author>
<Name>wwww</Name>
</Author>
<Source>移动采编</Source>
<DocContent>Wwwwwww</DocContent>
<StoryType>Text</StoryType>
</Story>
</SubFucParams>

html;

echo $aaa;
?>