if ($class->_is_start_pattern($line)) {
  # we have found the start of a customer record
  ...
}

sub _is_start_pattern {
  my ($class, $line) = @_;
  return ($line =~ $class->START_PATTERN);
  # I really wish we could do
  #return ($line =~ $class::START_PATTERN);
}
...

##</code><code>##

sub START_PATTERN {
  return qr(^(\d)\s+\1$);
}

##</code><code>##

sub END_PATTERN_1 {
  return qr(^<pattern for this division>$);
}

##</code><code>##

if ($class->_is_end_pattern_1($line) ||
    $class->_is_end_pattern_2($line)) {
  ...
}