There are two forms to the ARTICLE command (and the related BODY,
   HEAD, and STAT commands), each using a different method of specifying
   which article is to be retrieved.  When the ARTICLE command is
   followed by a message-id in angle brackets ("<" and ">"), the first
   form of the command is used; when a numeric parameter or no parameter
   is supplied, the second form is invoked.

   The text of the article is returned as a textual response, as
   described earlier in this document.

   The HEAD and BODY commands are identical to the ARTICLE command
   except that they respectively return only the header lines or text
   body of the article.

   The STAT command is similar to the ARTICLE command except that no
   text is returned.  When selecting by message number within a group,
   the STAT command serves to set the current article pointer without
   sending text. The returned acknowledgement response will contain the
   message-id, which may be of some value.  Using the STAT command to
   select by message-id is valid but of questionable value, since a
   selection by message-id does NOT alter the "current article pointer".

RFC977 3.1.1.  ARTICLE (selection by message-id)

   ARTICLE <message-id>

   Display the header, a blank line, then the body (text) of the
   specified article.  Message-id is the message id of an article as
   shown in that article's header.  It is anticipated that the client
   will obtain the message-id from a list provided by the NEWNEWS
   command, from references contained within another article, or from
   the message-id provided in the response to some other commands.

   Please note that the internally-maintained "current article pointer"
   is NOT ALTERED by this command. This is both to facilitate the
   presentation of articles that may be referenced within an article
   being read, and because of the semantic difficulties of determining
   the proper sequence and membership of an article which may have been
   posted to more than one newsgroup.

RFC977 3.1.2.  ARTICLE (selection by number)

   ARTICLE [nnn]

   Displays the header, a blank line, then the body (text) of the
   current or specified article.  The optional parameter nnn is the

   numeric id of an article in the current newsgroup and must be chosen
   from the range of articles provided when the newsgroup was selected.
   If it is omitted, the current article is assumed.

   The internally-maintained "current article pointer" is set by this
   command if a valid article number is specified.

   [the following applies to both forms of the article command.] A
   response indicating the current article number, a message-id string,
   and that text is to follow will be returned.

   The message-id string returned is an identification string contained
   within angle brackets ("<" and ">"), which is derived from the header
   of the article itself.  The Message-ID header line (required by
   RFC850) from the article must be used to supply this information. If
   the message-id header line is missing from the article, a single
   digit "0" (zero) should be supplied within the angle brackets.

   Since the message-id field is unique with each article, it may be
   used by a news reading program to skip duplicate displays of articles
   that have been posted more than once, or to more than one newsgroup.

RFC977 3.1.3.  Responses

   220 n <a> article retrieved - head and body follow
           (n = article number, <a> = message-id)
   221 n <a> article retrieved - head follows
   222 n <a> article retrieved - body follows
   223 n <a> article retrieved - request text separately
   412 no newsgroup has been selected
   420 no current article has been selected
   423 no such article number in this group
   430 no such article found