You can get the attributes of an XML element by calling the attributes() function on an XML node. You can then var_dump the return value of the function.
More info at php.net http://php.net/simplexmlelement.attributes
Example code from that page:
$xml = simplexml_load_string($string);
foreach($xml->foo[0]->attributes() as $a => $b) {
echo $a,'="',$b,"\"\n";
}