Newsgroups:

Newsgroups: ヘッダー (ネットニュース)

[2] Newsgroups: ヘッダーは、投稿先のニュースグループ名を指定するものです。

文脈

[6] ネットニュースメッセージで必ず用いられます。 それ以外の RFC 822メッセージでは用いられません。

歴史

[3] RFC 1036 2.1.3. Newsgroups

The "Newsgroups" line specifies the newsgroup or newsgroups in which the message belongs. Multiple newsgroups may be specified, separated by a comma. Newsgroups specified must all be the names of existing newsgroups, as no new newsgroups will be created by simply posting to them.

「Newsgrops」(新聞組)行には一つあるいは複数のメッセージが属する 新聞組を書きます。複数の新聞組を読点(コンマ)で区切って書いても構いません。 書く新聞組は全て存在する新聞組の名前でないといけません。 単に投稿するだけでは新しい新聞組は作られません。

Wildcards (e.g., the word "all") are never allowed in a "Newsgroups" line. For example, a newsgroup comp.all is illegal, although a newsgroup rec.sport.football is permitted.

ワイルドカード (例えば「all」(全て)という語) は「Newsgroups」 行では認められません。例えば、新聞組 rec.sport.football は認められますが、 comp.all は間違いです。

If a message is received with a "Newsgroups" line listing some valid newsgroups and some invalid newsgroups, a host should not remove invalid newsgroups from the list. Instead, the invalid newsgroups should be ignored. For example, suppose host A subscribes to the classes btl.all and comp.all, and exchanges news messages with host B, which subscribes to comp.all but not btl.all. Suppose A receives a message with Newsgroups: comp.unix,btl.general.

メッセージを「Newsgroups」行のうち幾つかは有効で、幾つかは 無効な新聞組である状態で受信した時、ホストは リストから無効な新聞組を削除するべきではありません。 そうではなく、無効な新聞組は無視するべきです。 例えば、ホスト A が級 btl.all 及び comp.all を読んでいて、 新聞メッセージを comp.all を読んでいるが btl.all は読んでいない ホスト B と交換しているとします。 A が「Newsgroup: comp.unix,btl.general」 と書かれたメッセージを受け取ったとします。

This message is passed on to B because B receives comp.unix, but B does not receive btl.general. A must leave the "Newsgroups" line unchanged. If it were to remove btl.general, the edited header could eventually re-enter the btl.all class, resulting in a message that is not shown to users subscribing to btl.general. Also, follow-ups from outside btl.all would not be shown to such users.

このメッセージは B に渡されます。 B は comp.unix を受け取るからです。 しかし B は btl.general は受け取りません。 A は「Newsgroups」行を 変更しないでおかなければなりません。もし btl.general が削除されたら、 いじられた頭が後に btl.all 級に再び入った時に、 btl.general を読んでいる利用者には見せられないことになります。 また、 btl.all の他からの返信もこの利用者は見れなくなります。

[4] son-of-RFC 1036 5.5. Newsgroups
          The Newsgroups header's content specifies which newsgroup(s)
          the article is posted to:
               Newsgroups-content  = newsgroup-name *( ng-delim newsgroup-name )
               newsgroup-name      = plain-component *( "." component )
               component           = plain-component / encoded-word
               plain-component     = component-start *13component-rest
               component-start     = lowercase / digit
               lowercase           = <letter a-z>
               component-rest      = component-start / "+" / "-" / "_"
               ng-delim            = ","

Encoded words used in newsgroup names MUST not contain characters other than letters, digits, "+", "-", "/", "_", "=", and "?" (although they may encode them).

新聞組名で使われる符号化語は文字 (訳注: ラテン文字 [a-z]), 数字, 「+」, 「-」, 「/」, 「_」, 「=」, 「?」以外のものから構成されては なりません (符号化するのは構いませんが)。

A newsgroup name consists of one or more components, which may be plain components or (except for the first) encoded words. A plain component MUST contain at least one letter, MUST begin with a letter or digit, and MUST not be longer than 14 characters. The first component MUST begin with a letter; subsequent components SHOULD begin with a letter. Newsgroup names MUST not contain uppercase letters, except where required by encodings in encoded words. The sequences "all" and "ctl" MUST not be used as components.

新聞組名は一つ以上の、平部品 (plain component) または(最初のを除いて) 符号化語から構成されます。平部品は最低1文字なければならず、 文字または数字で始まらなければならず、14文字より長くては なりません。最初の部品は文字で始まらなければなりません。 続く部品も文字で始めるべきであります。新聞組名には、 符号化語の符号化のために必要な場合を除いて、大文字を使っては いけません。文字列「all」および「ctl」は部品に使ってはいけません

NOTE: The alphabet and syntax specified encompasses all existing names of widespread newsgroups, while avoiding various forms that are known to cause problems. Important existing software uses various non-alphanumeric characters as punctuation adjacent to newsgroup names. (It would, in fact, be preferable to ban "+" from newsgroup names, were it not that several widespread newsgroups related to the C++ programming language already use it.)

参考: 字母及び構文仕様は、問題を起こすことが分かっている幾つかの ものを除いて全ての存在する広域新聞組の名前を含んでいます。 重要な既存ソフトウェアは幾つかの非英数字を並んでいる新聞組名の 区切りに使っています。 (実際のところ、 C++ プログラム言語に関係する 幾つかの広域新聞組が無ければ、「+」は新聞組名では禁止した方が 良かったでしょう。)

NOTE: Much existing software converts the newsgroup name into a directory path and stores the articles themselves using numeric filenames, so all-digit name components can be troublesome; the "Great Renaming" early in the history of Usenet included revisions of several newsgroup names to eliminate such components.

参考; 多くの既存ソフトウェアは新聞組名をディレクトリ経路に対応させ、 記事を数字のファイル名で保管しているので、全て数字の名前部品は 厄介なのです。 Usenet の歴史の早期の「大改名」(Great Renaming) は 幾つかの新聞組の名前から全数字部品を取り除く修正も含んでいました。

NOTE: The same storage technique is the reason for the 14-character limit. The limit is now largely historical, since most modern systems have much larger limits on the length of a directory entry's name, but many old systems are still in use. Systems with shorter limits also exist, but news software on such systems has had to deal with the problem already, since there are several widespread newsgroups with 14-character components in their names. Implementors are warned that it is intended that the successor to this Draft will increase the 14-character limit, and are urged to fix their software to handle longer names gracefully (if such fixes are necessary, given the intended domain of application of the particular software).

参考: 上述の保管法が14文字制限の理由です。この制限はほとんどの現代系統の ディレクトリ項目名の長さの制限が比較的長いものになったので、 最早過去のものになりつつあります。しかし多くの古い系統がまだ使われています。 短い制限の系統もありますが、そのような系統のニュース・ソフトウェアは 既に問題を処理しなければならなくなっています。14文字の部品を持った 広域新聞組が幾つかあるからです。実装者には、この'原案'の改訂版では 14文字制限を増やす予定であることを予告し、ソフトウェアを長い名前を素直に 扱えるように修正することをお勧めします。(そのような修正が必要なら、 特定ソフトウェアの応用の意図した範囲に対して。)

NOTE: The requirement that the first character of a name be a letter accommodates existing software which assumes it can tell the difference between a

               newsgroup name and other possible syntactic  enti-
               ties  by  inspecting the first character.  Similar
               considerations motivate excluding  "+",  "-",  and
               "_"  from  coming  first  in  a component, and the
               preference for components that do not  begin  with
               digits.   The "all" sequence is used as a wildcard
               symbol in much existing software,  and  the  "ctl"
               sequence  was  involved  in an obsolete historical
               mechanism for marking control  messages,  so  they
               are best avoided.

参考: 名前の先頭文字を文字に限るという制限は、新聞組名と他の構文的実体を 先頭文字で区別できると仮定する既存ソフトウェアの便宜をはかるためのものです。 「+」, 「-」, 「_」を部品の先頭から外したり、数字で始まらない 部品を推奨するのも同様の考慮からです。「all」列は多くの既存ソフトウェアで ワイルドカード記号として使われていて、「ctl」列は制御メッセージを 識別する古い歴史的な機構で使われているので、避けるのが一番なのです。

               NOTE:  Possibly  newsgroup  names should have been
               case-insensitive, but all existing software treats
               them  as  case-sensitive.   (RFC  977 [rrr] claims
               that they are case-insensitive in NNTP, but exist-
               ing  implementations are believed to ignore this.)
               The simplest solution is just to ban use of upper-
               case  letters,  since no widespread newsgroup name
               uses them anyway; this avoids any  possibility  of
               confusion.

参考: 可能なら新聞組名は大文字・小文字を区別しないべきですが、 全ての既存ソフトウェアは大文字・小文字を区別するものと扱います。 (RFC 977 は NNTP では区別しないことを要求していますが、 既存実装はこれを無視していると考えられます。) 最も単純な解は、 広域新聞組名で大文字を使っている所が無いので、大文字の使用を 禁止することでしょう。これにより混乱の可能性を排除できます。

               NOTE:  The syntax has the disadvantage of contain-
               ing no white space, making it impossible  to  con-
               tinue  a  Newsgroups  header across several lines.
               Implementors of relayers and  reading  agents  are
               warned  that  it is intended that the successor to
               this Draft will change the definition of  ng-delim
               to:

参考: 構文では空白間隔を含んでいないので、 Newsgroups 頭を 複数行に分けて継続することが出来ないという問題点があります。 中継ソフトウェアと読み代理者の実装者には、この'原案'の改訂版では ng-delim の定義を次のように変更することを予告します。

                    ng-delim = "," [ space ]
               and  are  urged  to  fix  their software to handle
               (i.e., ignore) white space following  the  commas.
               Meanwhile, posters must avoid inserting such space
               (despite  the  natural-language  convention  which
               permits  it)  and  posting  agents should strip it
               out.

読点(コンマ)に続く空白間隔を扱う(無視する)ようにソフトウェアを修正することを お勧めします。一方、投稿者は、間隔を挿入することを (自然言語での 慣習が認めているけど) 避けなければならず、投稿代理者は 取り除くべきです。

               NOTE: Encoded words  as  components  are  somewhat
               problematic,  but are clearly desirable for use in
               non-English-speaking nations.  They are  not  sub-
               ject to the 14-character limit, and this (plus the
               possibility of "/" within them) may  require  spe-
               cial handling in news software.

参考: 符号化語は部品としてはやや問題がありますが、非英話国では 使用することが望ましいのは明らかです。これは14文字制限の関する所 ではなく、またこのこと (及び「/」が含まれる可能性のあること) は ニュース・ソフトウェアで特別な取り扱いが必要かもしれません。

          Encoded words are allowed in newsgroup names ONLY where non-
          ASCII characters are necessary to the name, and must use the
          "b"  encoding  [rrr] and the first suitable character set in
          the MIME order of preferred character sets [rrr].

符号化語は新聞組名中では非 ASCII 文字が名前に必要な所でのみ 認められ、「b」符号化方法と優先文字集合の MIME 順で最初の適切な 文字集合で無ければなりません。

               NOTE: Since the  newsgroup  name  is  the  encoded
               form,  NOT the underlying non-ASCII form, there is
               room for terrible confusion here if the choice  of
               encoding  for a particular name is not fully stan-
               dardized.
          Posters SHOULD use only the names of existing newsgroups  in
          the  Newsgroups  header,  because newsgroups are NOT created
          simply by being posted to.  However,  it  is  legitimate  to
          cross-post to newsgroup(s) which do not exist on the posting
          agent's host, provided that at least one of  the  newsgroups
          DOES  exist  there,  and  followup  agents  MUST accept this
          (posting agents MAY accept it, but SHOULD at least alert the
          poster to the situation and request confirmation).  Relayers
          MUST not rewrite Newsgroups headers in any way, even if some
          or all of the newsgroups do not exist on the relayer's host.
               NOTE: Early experience  with  news  software  that
               created  newsgroups  when they were mentioned in a
               Newsgroups header was thoroughly negative: posters
               frequently mistype newsgroup names.
               NOTE:  While it is legitimate for some of an arti-
               cle's newsgroups not to exist on the host where it
               is  posted,  this  IS  a  rather unusual situation
               except in followups (which should go to all  news-
               groups  the  precursor  was posted to, even if not
               all of them reach the site where the  followup  is
               being posted).
               NOTE:   Rewriting   Newsgroups  headers  to  strip
               locally-unknown   newsgroups   is    superficially
               attractive.    However,   early   experience  with
               exactly that policy was thoroughly negative:  news
               propagation   is  more  redundant  and  much  less
               orderly than many people imagine, and in  particu-
               lar  it  is  not  unheard-of  for  the (sometimes)
               fastest path between two (say) U of Toronto  sites
               to  pass  outside  U  of  Toronto... in which case
               newsgroup stripping can cause incomplete  propaga-
               tion.   Having  an  article's  set  of  newsgroups
               change as it propagates can also  result  in  fol-
               lowups  not  achieving the same propagation as the
               original.  It's been tried; it's more trouble than
               it's worth; don't do it.
               NOTE:  In particular, newsgroup stripping superfi-
               cially looks like a solution  to  the  problem  of
               duplicate  regional newsgroup names.  For example,
               both University of Toronto and University of Texas
               have  "ut.general" newsgroups, and material cross-
               posted to that name and a global newsgroup appears
               in  both universities' local newsgroups.  However,
               the side effects  of  stripping  are  sufficiently
               unacceptable  to  disqualify  it for this purpose.
               Don't do it.
          Cross-posting an article to several relevant  newsgroups  is
          far  superior  to  posting separate articles with duplicated
          content to each newsgroup, because reading agents can detect
          the  situation  and  show the article to a reader only once.
          Posters SHOULD cross-post rather than duplicate-post.
               NOTE: On the other hand, cross-posting to a  large
               number  of  newsgroups  usually indicates that the
               poster has not thought about his  audience;  arti-
               cles  are rarely pertinent to more than (say) half
               a dozen newsgroups.  Posting agents might wish  to
               request confirmation when the number of newsgroups
               exceeds (say) five in the presence of a  Followup-
               To  header,  or (say) two in the absence of such a
               header.
               NOTE: One problem with cross-postings is  what  to
               do  with an article cross-posted to a set of news-
               groups including both  moderated  and  unmoderated
               ones.   Posters  tend to expect such an article to
               show up immediately in the unmoderated newsgroups,
               especially if they do not realize that one or more
               of the newsgroups is moderated.  However, since it
               is  not  possible for a moderator to retroactively
               add an already-posted article to a moderated news-
               group,  the only correct action is to mail such an
               article to one (and only one)  of  the  moderators
               for  action.   It is probably best for the posting
               agent to detect this situation and ask the  poster
               what  action is preferred.  The acceptable choices
               are to alter the newsgroup list or to  mail  to  a
               moderator  of  the  poster's  choice;  the posting
               agent should NOT  offer  duplicate-posting  as  an
               easy-to-request  option (if only because many mod-
               erators will reject a submission that has  already
               been posted to unmoderated newsgroups).
               NOTE:  An  article cross-posted to multiple moder-
               ated newsgroups really should have  approval  from
               all  the  moderators  involved.   In practice, the
               only straightforward way to do this is to send the
               article  to  one  of them and have him consult the
               others.
          A newsgroup SHOULD not appear more than once  in  the  News-
          groups header.
          Newsgroup  names  having only one component are reserved for
          newsgroups whose propagation is restricted to a single  host
          (or  the  administrative  equivalent).  It is inadvisable to
          name a newsgroup "poster"  because  that  word  has  special
          meaning  in  the  Followup-To header (see section 6.1).  The
          names "control" and "junk" are frequently used  for  pseudo-
          newsgroups  internal  to  relayer implementations, and hence
          are also best avoided.
               NOTE: Beware of the  duplicate-regional-newsgroup-
               names  problem  mentioned  above.   In particular,
               there are many, many hosts with a newsgroup  named
               "general",  and  some surprising things show up in
               such newsgroups when  people  cross-post.   It  is
               probably  better  to  use  multi-component  names,
               which are less likely to  be  duplicated.   Fred's
               Widget  House should use "fwh.general" rather than
               just  "general"  as  its  in-house  general-topics
               newsgroup.
          It is conventional to reserve newsgroup names beginning with
          "to." for test messages sent  on  an  essentially  point-to-
          point basis (see also the ihave/sendme protocol described in
          section 7.2); newsgroup names beginning  with  "to."  SHOULD
          not be used for any other purpose.  The second (and possibly
          later) components of such a name should, together,  comprise
          the  relayer name (see section 5.6) of a relayer.  The news-
          group exists only at the named relayer  and  its  neighbors.
          The  neighbors all pass that newsgroup to the named relayer,
          while the named relayer does not pass it to anyone.

The order of newsgroup names in the Newsgroups header is not significant.

Newsgroups 頭での新聞組名の順序に意味はありません。

[5] son-of-RFC1036, draft-usefor-article (06) から

  Newsgroups-content  = newsgroup-name
                        *([FWS] ng-delim [FWS] newsgroup-name) [FWS]
  Followup-To-content = Newsgroups-content / "poster"
  ng-delim            = ","