XML::Dumper, XML::Writer, XML::Writer::Simple ...

  # example using XML::Dumper

  use XML::Dumper;

  my $dump = new XML::Dumper;
  my $perl = ( 
              # some perl data structure 
             );
  $dump->dtd( $file, $url );
  my $xml_with_link_to_dtd = $dump->pl2xml( $perl );

  # example using XML::Writer::Simple

  use XML::Writer::Simple dtd => "file.dtd";

  print para("foo",b("bar"),"zbr");
  # Asuming para. etc are defined in the DTD
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XML::Dumper has the advantage of providing both read and write interfaces ...