map substr($_, 16),
    sort
    map {
       my ($x, $y, $z) = /_(\d+)_pg_(\d+)_(\d+\.\d+)/i or die;
       $z = sprintf("%.5f", $z);
       my ($zi, $zd) = split(/\./, $z);
       pack("NNNNa*", $x, $y, $zi, $zd, $_)
    }