#$rpt is just a namespace number retrieved from sub and is correct for each file.
$nsdevices="//ns" . $rpt. ":device";
my @devices = $doc->findnodes($nsdevices);
print "nsdevices:$nsdevices\n";

##</code><code>##

<?xml version='1.0' encoding='utf-8'?><Notify xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://docs.oasis-open.org/wsn/b-2">
<NotificationMessage>
<Topic Dialect="http://docs.oasis-open.org/wsn/t-1/TopicExpression/Simple">TOPICNAME</Topic>
<ProducerReference>
<Address xmlns="http://www.w3.org/2005/08/addressing">address</Address>
<Metadata xmlns="http://www.w3.org/2005/08/addressing">
<ns2:MessageID xmlns:ns2="http://www.w3.org/2005/08/addressing">msgid</ns2:MessageID>
</Metadata>
</ProducerReference>
<Message>
<ns1:rpt xmlns:ns1="http://www.url.com/path/for/rpt">
<ns1:reportObject>
<ns1:device timestamp="2016-01-01T00:00:00.000-00:00">