open( OUTPUT_XML_A_OPEN, $output_XML_A_open );
open( NEW_OUTPUT_XML_A, "+>>", $new_output_xml_a );
for $d ( 1..9 ) {
  seek( OUTPUT_XML_A_OPEN, 0, 0 );
  while (<OUTPUT_XML_A_OPEN>) {
    chomp;   # I'm leaving out a lot of your debugging stuff
    if( /^$d\D/ ) {  # does this line start with "$d"?
      print NEW_OUTPUT_XML_A;
    }
  }
}