Solution seems to be:
Adding the following lines to my PHP-script:
header('Content-Type: text/xml, charset=utf-8');
header('Content-Disposition: inline; filename=mijndummy.xml');
The second seems to be required for IExplorer. The reason is given in a post I found on
http://nl3.php.net/header:
dracolytch at yahoo dot com
10-May-2007 06:00
You may find that you want to process a PHP file, and have the browser treat the output as an XML file. Unfortunately, most browsers will only do this if the file extension is ".xml"
In those situations where you can't/don't want to change your apache config to put XML files through the PHP processor, you can use the header function to change the output to something the browser will recognise as XML:
header('Content-Type: text/xml');
header('Content-Disposition: inline; filename=sample.xml');
(The inline portion helps ensure the browser renders the page itself, instead of prompting the user to download the page)
