escaping colons in strings

Hi all,

I am trying to write to an XML file, but it will not allow me to use a
colon. Is there some way to be able to write the colon to the XML?

PHP code -
$point = "something"
$sitemap->addChild("new:point", $point);

XML it creates -
<point>something</point>

(misses the the 'new' all together)


Any ideas would be great,


Kind regards,

Chris