If you wanted to use XML::libXML then the following would point you toward the node you want:

my $parser = XML::LibXML->new();
my $doc = $parser->parse_file($data);
my ($object) = $doc->findnodes("\/e\/p\[\@v=\"YES\"\]");
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Then you can manipulate the rest all you want with the other functions (I would start with childnodes)
Hope this helps!
NOTE: I chose the double quotes in case you wanted to replace YES with a variable. Maybe . . .

my ($object) = $doc->findnodes("\/e\/p\[\@v=\"$criteria\"\]");
[download]