SimpleXMLElement two name spaces in a single element

You might find this related answer useful.

A namespace is ultimately identified only by its full URI; the etsi prefix might change meaning halfway down the document. The way SimpleXML has been designed, you have to mention this full URI every time you add a namespaced element or attribute.

On the other hand, you don't need to manually add the xmlns:etsi attribute; SimpleXML will add that automatically when you first use the namespace.

In other words, you have to write:

 $xml->addChild('etsi:QualifyingProperties', null, 'http://uri.etsi.org/01903/v1.3.2#'); 

And SimpleXML will generate this if it's the first time you've mentioned that namespace:

<etsi:QualifyingProperties xmlns:etsi="http://uri.etsi.org/01903/v1.3.2#" /> 

Or just this if the prefix etsi is already defined with the right value at that point in the document:

<etsi:QualifyingProperties /> 

Obviously, it's tedious to write out the full URI over and over, but that can be resolved simply by having a variable or constant in your code with a name that means something to you, like this:

define('XMLNS_ETSI_132', 'http://uri.etsi.org/01903/v1.3.2#'); $xml->addChild('etsi:QualifyingProperties', null, XMLNS_ETSI_132);