2.  Message Format

    The primary consideration in choosing a message format is that it
    fit in with existing tools as well as possible.  Existing tools
    include implementations of both mail and news.  (The notesfiles
    system from the University of Illinois is considered a news
    implementation.)  A standard format for mail messages has existed
    for many years on the Internet, and this format meets most of the
    needs of USENET.  Since the Internet format is extensible,
    extensions to meet the additional needs of USENET are easily made
    within the Internet standard.  Therefore, the rule is adopted that
    all USENET news messages must be formatted as valid Internet mail
    messages, according to the Internet standard RFC-822.  The USENET
    News standard is more restrictive than the Internet standard,
    placing additional requirements on each message and forbidding use
    of certain Internet features.  However, it should always be possible
    to use a tool expecting an Internet message to process a news
    message.  In any situation where this standard conflicts with the
    Internet standard, RFC-822 should be considered correct and this
    standard in error.

    Here is an example USENET message to illustrate the fields.

              From: jerry@eagle.ATT.COM (Jerry Schwarz)
              Path: cbosgd!mhuxj!mhuxt!eagle!jerry
              Newsgroups: news.announce
              Subject: Usenet Etiquette -- Please Read
              Message-ID: <642@eagle.ATT.COM>
              Date: Fri, 19 Nov 82 16:14:55 GMT
              Followup-To: news.misc
              Expires: Sat, 1 Jan 83 00:00:00 -0500
              Organization: AT&T Bell Laboratories, Murray Hill

              The body of the message comes here, after a blank line.

      Here is an example of a message in the old format (before the
      existence of this standard). It is recommended that
      implementations also accept messages in this format to ease upward
      conversion.

               From: cbosgd!mhuxj!mhuxt!eagle!jerry (Jerry Schwarz)
               Newsgroups: news.misc
               Title: Usenet Etiquette -- Please Read
               Article-I.D.: eagle.642
               Posted: Fri Nov 19 16:14:55 1982
               Received: Fri Nov 19 16:59:30 1982
               Expires: Mon Jan 1 00:00:00 1990

               The body of the message comes here, after a blank line.

      Some news systems transmit news in the A format, which looks like
      this:

                Aeagle.642
                news.misc
                cbosgd!mhuxj!mhuxt!eagle!jerry
                Fri Nov 19 16:14:55 1982
                Usenet Etiquette - Please Read
                The body of the message comes here, with no blank line.

    A standard USENET message consists of several header lines, followed
    by a blank line, followed by the body of the message.  Each header
    line consist of a keyword, a colon, a blank, and some additional
    information.  This is a subset of the Internet standard, simplified
    to allow simpler software to handle it.  The "From" line may
    optionally include a full name, in the format above, or use the
    Internet angle bracket syntax.  To keep the implementations simple,
    other formats (for example, with part of the machine address after
    the close parenthesis) are not allowed.  The Internet convention of
    continuation header lines (beginning with a blank or tab) is
    allowed.

    Certain headers are required, and certain other headers are
    optional.  Any unrecognized headers are allowed, and will be passed
    through unchanged.  The required header lines are "From", "Date",
    "Newsgroups", "Subject", "Message-ID", and "Path".  The optional
    header lines are "Followup-To", "Expires", "Reply-To", "Sender",
    "References", "Control", "Distribution", "Keywords", "Summary",
    "Approved", "Lines", "Xref", and "Organization".  Each of these
    header lines will be described below.

2.1.  Required Header lines

     From
     Date
     Newsgroups
     Subject
     Message-ID
     Path

2.2.  Optional Headers

     Reply-To
     Sender
     Followup-To
     Expires
     References
     Control
     Distribution
     Organization
     Keywords
     Summary
     Approved
     Lines
     Xref