Hi,
This line :
<?xml version="1.0" encoding="iso-8859-1"?>
Is a sort of header in a file. This want to say :
The whole file is just that, a xml file, and the data are stored as xml version 1.0 with the charset iso-8859-1
Normaly, if your file is a php script, it should not start with this line.
HTH,