anchor.diff:  %%                 integer()
   %%
   %% @type message_id() = integer()
  +%%
  +%% @type questions() = [query()]
  +%%
  +%% @type query() = #dns_query{name = dname(),
  +%%                            class = class(),
  +%%                            type = type()}
  +%%
  +%% @type answers() = [rr()]
  +%%
  +%% @type authority() = [rr()]
  +%%
  +%% @type additional() = [optrr() | rr()]
  +%%
  +%% @type rr() = #dns_rr{name = dname(),
  +%%                      class = class(),
  +%%                      type = type(),
  +%%                      ttl = ttl(),
  +%%                      data = rrdata()}
  +%%
  +%% @type dname() = binary() | string()
  +%%
  +%% @type class() = 'in' | 'cs' | 'ch' | 'hs' | 'none' | 'any' | integer()
  +%%
  +%% @type type() = 'a' |
  +%%                'aaaa' |
  +%%                'afsdb' |
  +%%                'apl' |
  +%%                'atma' |
  +%%                'axfr' |
  +%%                'cert' |
  +%%                'cname' |
  +%%                'dhcid' |
  +%%                'dlv' |
  +%%                'dname' |
  +%%                'dnskey' |
  +%%                'ds' |
  +%%                'eid' |
  +%%                'gid' |
  +%%                'gpos' |
  +%%                'hinfo' |
  +%%                'hip' |
  +%%                'ipseckey' |
  +%%                'isdn' |
  +%%                'ixfr' |
  +%%                'key' |
  +%%                'kx' |
  +%%                'loc' |
  +%%                'maila' |
  +%%                'mailb' |
  +%%                'mb' |
  +%%                'md' |
  +%%                'mf' |
  +%%                'mg' | 
  +%%                'minfo' |
  +%%                'mr' |
  +%%                'mx' |
  +%%                'naptr' |
  +%%                'nimloc' |
  +%%                'ninfo' |
  +%%                'ns' |
  +%%                'nsap' |
  +%%                'nsec' |
  +%%                'nsec3' |
  +%%                'nsec3param' |
  +%%                'null' |
  +%%                'nxt' |
  +%%                'opt' |
  +%%                'ptr' |
  +%%                'px' |
  +%%                'rkey' |
  +%%                'rp' |
  +%%                'rrsig' |
  +%%                'rt' |
  +%%                'sig' |
  +%%                'sink' |
  +%%                'soa' |
  +%%                'spf' |
  +%%                'srv' |
  +%%                'sshfp' |
  +%%                'talink' |
  +%%                'tkey' |
  +%%                'tsig' |
  +%%                'txt' |
  +%%                'uid' |
  +%%                'uinfo' |
  +%%                'unspec' |
  +%%                'wks' |
  +%%                'x25' |
  +%%                integer()
  +%%
  +%% @type optrr() = #dns_opt_rr{udp_payload_size = integer(),
  +%%                             ext_rcode = ext_rcode(),
  +%%                             version = integer(),
  +%%                             dnssec = bool(),
  +%%                             data = optrrdata()}
  +%%
  +%% @type ext_rcode() = badvers | integer()
  +%%
  +%% @type rrdata() =  dns_rrdata_a() |
  +%%                   dns_rrdata_aaaa() |
  +%%                   dns_rrdata_afsdb() |
  +%%                   dns_rrdata_cert() |
  +%%                   dns_rrdata_cname() |
  +%%                   dns_rrdata_dhcid() |
  +%%                   dns_rrdata_dlv() |
  +%%                   dns_rrdata_dname() |
  +%%                   dns_rrdata_dnskey() |
  +%%                   dns_rrdata_ds() |
  +%%                   dns_rrdata_hinfo() |
  +%%                   dns_rrdata_ipseckey() |
  +%%                   dns_rrdata_isdn() |
  +%%                   dns_rrdata_key() |
  +%%                   dns_rrdata_kx() |
  +%%                   dns_rrdata_loc() |
  +%%                   dns_rrdata_mb() |
  +%%                   dns_rrdata_md() |
  +%%                   dns_rrdata_mf() |
  +%%                   dns_rrdata_mg() |
  +%%                   dns_rrdata_minfo() |
  +%%                   dns_rrdata_mr() |
  +%%                   dns_rrdata_mx() |
  +%%                   dns_rrdata_naptr() |
  +%%                   dns_rrdata_ns() |
  +%%                   dns_rrdata_nsec() |
  +%%                   dns_rrdata_nsec3() |
  +%%                   dns_rrdata_nsec3param() |
  +%%                   dns_rrdata_nxt() |
  +%%                   dns_rrdata_ptr() |
  +%%                   dns_rrdata_rp() |
  +%%                   dns_rrdata_rrsig() |
  +%%                   dns_rrdata_rt() |
  +%%                   dns_rrdata_soa() |
  +%%                   dns_rrdata_spf() |
  +%%                   dns_rrdata_srv() |
  +%%                   dns_rrdata_sshfp() |
  +%%                   dns_rrdata_tsig() |
  +%%                   dns_rrdata_txt() |
  +%%                   dns_rrdata_wks() |
  +%%                   dns_rrdata_x25()
  +%%
   -record(dns_message, {id = dns:random_id(),
   		      qr = false,
   		      oc = 'query',
  
positive.code: %%                                answers = answers(),
  %%                                authority = authority(),
  %%                                additional = additional()}.
  %% <ul>
  %% <li>qr - Query Response</li>
  %% <li>oc - Opcode</li>
  
negative.code: 		      answers = [],
  		      authority = [],
  		      additional=[] }).
  
  -record(dns_query, {name, class = in, type}).
  
  -record(dns_rr, {name, class = in, type, ttl = 0, data}).
  -record(dns_rrdata_a, {ip}).
  -record(dns_rrdata_aaaa, {ip}).
  -record(dns_rrdata_afsdb, {subtype, hostname}).
  -record(dns_rrdata_cert, {type, key_tag, alg, cert}).
  -record(dns_rrdata_cname, {dname}).
  -record(dns_rrdata_dhcid, {data}).
  -record(dns_rrdata_dlv, {keytag, alg, digest_type, digest}).
  -record(dns_rrdata_dname, {dname}).
  -record(dns_rrdata_dnskey, {flags, protocol, alg, public_key, key_tag}).
  -record(dns_rrdata_ds, {keytag, alg, digest_type, digest}).
  -record(dns_rrdata_hinfo, {cpu, os}).
  -record(dns_rrdata_ipseckey, {precedence,
  			      alg,
  			      gateway_type,
  			      gateway,
  			      public_key}).
  -record(dns_rrdata_isdn, {address, subaddress}).
  -record(dns_rrdata_key, {type, xt, name_type, sig, protocol, alg, public_key}).
  -record(dns_rrdata_kx, {preference, exchange}).
  -record(dns_rrdata_loc, {size, horiz, vert, lat, lon, alt}).
  -record(dns_rrdata_mb, {madname}).
  -record(dns_rrdata_md, {madname}).
  