$/ = undef;
while (<>) {

    print "\n$ARGV\n", / (.+?) ^.*^ (.+?) \z/xms
}




##</code><code>##

$dtrx = qr/[Dd][Tt]=(\d{8}\.\d{6})/;
$/ = undef;
while (<>) {

  ($aa, $z) = /$dtrx          # get the first one
               (?:            # and maybe,
                 .*           # after maybe many lines,
                 ^.*? $dtrx   # the first one on the last line
               )?             #   that has one
              /mxs;
  $aa or next;
  $z ||= '';                  # or '' if no more

  print "$ARGV\t $aa -- $z\n";
}