xml and php ???

[techbud]

Hello everyone,,
I am a bloody beginner referring to xml.

How can I connect xml and php in one file ???

This line is given as flawed: 55printing . com
<? Xml version = "1.0" encoding = "iso-8859-1"?>

Parse error: parse error, unexpectedly T_STRING in

I have php and xml code in a file.
this file ends with .php
is that correct ???

let me end the file with .html will show me the php-code instead of running it.

MfG.