XML inside PHP pages?

Hi all,
	I'm having some trouble with PHP includes in my otherwise happy XHTML 1.0 
Transitional documents, the problem being that the topmost tag on the page, 
right above the doctype declaration, uses a PHP tag format to do its deed: 
<?xml version="1.0" encoding="iso-8859-1"?> - so the parser chokes on the 
'invalid PHP'. A simple line, and my (*.php) pages still validate as 
W3C-happy XHTML without it, but I'd rather keep to the guidelines in hope 
of improving forwards-compatibility. Does anyone have a workaround for this?

Cheers,
-nialoo
-atomkinder.net