usefor-article-04 April 2001

5.5.  Newsgroups

   The Newsgroups header's content specifies the newsgroup(s) in which
   the article is intended to appear. It is an inheritable header
   (4.2.2.2) which then becomes the default Newsgroups header of any
   followup, unless a Followup-To header is present to prescribe
   otherwise.

      Newsgroups-content  = newsgroup-name
                     *( *FWS ng-delim *FWS newsgroup-name )
                     *FWS
      newsgroup-name      = component *( "." component )
      component           = component-start
                     *( component-start / component-other )
      component-start     = Un-lowercase / Un-digit
      Un-lowercase        = <Unicode Letter, Lowercase> /
                  <Unicode Letter, Other>
      Un-digit            = <Unicode Number, Decimal Digit> /
                  <Unicode Number, Other>
      component-other     = "+" / "-" / "_"
      ng-delim            = ","
   where the <Unicode ...> items are as described in [UNICODE].

   The inclusion of folding white space within a Newsgroups-content is a
   newly introduced feature in this standard. It MUST be accepted by all
   conforming implementations (relaying agents, serving agents and
   reading agents).  Posting agents should be aware that such postings
   may be rejected by overly-critical old-style relaying agents. When a
   sufficient number of relaying agents are in conformance, posting
   agents SHOULD generate such whitespace in the form of <CRLF WS> so as
   to keep the length of lines in the relevant headers (notably
   Newsgroups and Followup-To) to no more than than 79 characters (or
   other agreed policy limit - see 4.5).  Before such critical mass
   occurs, injecting agents MAY reformat such headers by removing
   whitespace inserted by the posting agent, but relaying agents MUST
   NOT do so.

   A newsgroup-name consists of one or more components. Components MAY
   contain non-ASCII letters, but these MUST be encoded in UTF-8 and not
   according to [RFC 2047].  A component MUST contain at least one
   letter (and MUST, according to the syntax, begin with a letter or
   digit). Components SHOULD begin with a letter.  Composite characters
   (made by overlaying one character with another) and format
   characters, as allowed in certain parts of Unicode and needed by
   certain languages, must use whatever canonical conventions apply to
   those parts of Unicode (such conventions are not defined in this
   Standard). The use of "_" in a component is deprecated. Serving
   agents MAY refuse to accept newsgroups using such a component.

        NOTE: Components composed entirely of digits would cause
        problems for the commonly used implementation technique of using
        the component as the name of a directory, whilst also using
        sequential numbers to distinguish the articles within a group.
        Components containing other non-permitted characters could cause
        problems when newsgroup-names appear in URLs [RFC 1738] (for
        example an '@' character would prevent distinguishing between
        newsgroup-names and message identifiers).

        NOTE: According to the syntax, uppercase letters cannot occur in
        newsgroup-names, but this standard imposes no requirement on
        software to check this condition, since it would be unreasonable
        to expect it to do so in parts of Unicode for which it was not
        configured (in general, a table lookup is required). Rather, it
        is the responsibility of those creating new newsgroups (7.1) not
        to violate it. It is, moreover, to be expected that a newsgroup
        created in violation of this condition will not be propagated
        particularly well.

   Whilst there is no longer any technical reason to limit the length of
   a component (formerly, it was limited to 14 characters) nor to limit
   the total length of a newsgroup-name, it should be noted that these
   names are also used in the newsgroups line (7.1.2) where an overall
   policy limit applies, and moreover excessively long names can be
   exceedingly inconvenient in practical use.  Agencies responsible for
   individual hierarchies Ought therefore, as a matter of policy, to set
   reasonable limits for the length of a component and of a newsgroup-
   name. In the absence of such explicit policies, the default limits
   are 30 characters and 71 characters respectively.
[If the checkpolicies proposal is included in the Standard, there should
be a reference to it here.]

        NOTE: The newsgroup-name as encoded in UTF-8 should be regarded
        as the canonical form. Reading agents may convert it to whatever
        character set they are able to display (see 4.4.1) and serving
        agents may possibly need to convert it to some form more
        suitable as a filename. Simple algorithms for both kinds of
        conversion are readily available.  Observe that the syntax does
        not allow comments within the Newsgroups header; this is to
        simplify processing by relaying and serving agents which have a
        requirement to process this header extremely rapidly.

   Posters SHOULD use only the names of existing newsgroups in the
   Newsgroups header. 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 SHOULD accept this (posting agents MAY accept it, but Ought at
   least to alert the poster to the situation and request confirmation).
   Relaying agents MUST NOT rewrite Newsgroups headers in any way, even
   if some or all of the newsgroups do not exist on the relaying agent's
   host. Serving agents MUST NOT create new newsgroups simply because an
   unrecognised newsgroup-name occurs in a Newsgroups header (see 7.1
   for the correct method of newsgroup creation).

   The Newsgroups header is intended for use in Netnews articles rather
   than in mail messages. It MAY be used in a mail message to indicate
   that it is a copy also posted to the listed newsgroups, but it SHOULD
   NOT be used in a mail-only reply to a Netnews article (thus the
   "inheritable" property of this header applies only to followups to a
   newsgroup, and not to followups to the poster). Moreover, if a
   newsgroup-name contains any non-ASCII character, it MAY be encoded
   using the mechanism defined in [RFC 2047] when sent by mail but, if
   it is subsequently returned to the Netnews environment, it MUST then
   be re-encoded into UTF-8.

--- ../usefor-article-03/Newsgroups.out          February 2000
+++ ../usefor-article-04/Newsgroups.out          April 2001
@@ -1,9 +1,10 @@
 5.5.  Newsgroups
 
-   The Newsgroups header's content specifies which newsgroup(s) the
-   article is posted to. It is an inheritable header (4.2.2.2) which
-   SHOULD then become the default Newsgroups header of any followup,
-   unless a Followup-To header is present to prescribe otherwise.
+   The Newsgroups header's content specifies the newsgroup(s) in which
+   the article is intended to appear. It is an inheritable header
+   (4.2.2.2) which then becomes the default Newsgroups header of any
+   followup, unless a Followup-To header is present to prescribe
+   otherwise.
 
       Newsgroups-content  = newsgroup-name
                      *( *FWS ng-delim *FWS newsgroup-name )
@@ -71,12 +72,13 @@
    names are also used in the newsgroups line (7.1.2) where an overall
    policy limit applies, and moreover excessively long names can be
    exceedingly inconvenient in practical use.  Agencies responsible for
-   individual hierarchies SHOULD therefore, as a matter of policy, set
+   individual hierarchies Ought therefore, as a matter of policy, to set
    reasonable limits for the length of a component and of a newsgroup-
-   name. In the absence of such explicit policies, the default figures
+   name. In the absence of such explicit policies, the default limits
    are 30 characters and 71 characters respectively.
 [If the checkpolicies proposal is included in the Standard, there should
 be a reference to it here.]
+
         NOTE: The newsgroup-name as encoded in UTF-8 should be regarded
         as the canonical form. Reading agents may convert it to whatever
         character set they are able to display (see 4.4.1) and serving
@@ -91,8 +93,8 @@
    Newsgroups header. 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 SHOULD accept this (posting agents MAY accept it, but SHOULD
-   at least alert the poster to the situation and request confirmation).
+   agents SHOULD accept this (posting agents MAY accept it, but Ought at
+   least to alert the poster to the situation and request confirmation).
    Relaying agents MUST NOT rewrite Newsgroups headers in any way, even
    if some or all of the newsgroups do not exist on the relaying agent's
    host. Serving agents MUST NOT create new newsgroups simply because an