Dear Monks,
I need to sort the lines that start with "<ref" and with in the <address>...</address> range. The text outside <address>...</address> should remain untouched. But my present code sorts the entire file. please help me in fixing this. 
$/ = "</address>\n";
while ( <DATA> ) {
    chomp;
    print "$_\n" for sort { $a cmp $b} split /\n/;
    print $/ if ! eof DATA;
}


__DATA__
xxx data
aaa data
<address>
<state>address1</state>
<ref refid="aff1">1</ref>
<ref refid="aff2">2</ref>
<ref refid="e2"/>
<ref refid="e4"/>
<ref refid="aff4">4</ref>
</address>
<address>
<state>address1</state>
<ref refid="aff1">1</ref>
<ref refid="aff2">2</ref>
<ref refid="e4"/>
<ref refid="aff3">3</ref>
</address>
xxx data
aaa data

[download]
desired output:
xxx data
aaa data
<address>
<state>address1</state>
<ref refid="aff1">1</ref>
<ref refid="aff2">2</ref>
<ref refid="aff4">4</ref>
<ref refid="e2"/>
<ref refid="e4"/>
</address>
<address>
<state>address1</state>
<ref refid="aff1">1</ref>
<ref refid="aff2">2</ref>
<ref refid="aff3">3</ref>
<ref refid="e4"/>
</address>
xxx data
aaa data

[download]
Thanks in advance

In reply to difficulty in sorting by texuser74

Title:
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