rfc1036 December 1987

3.5.  Sendsys
                 sendsys (no arguments)

    The sys file, listing all neighbors and the newsgroups to be sent to
    each neighbor, will be mailed to the author of the control message
    ("Reply-To", if present, otherwise "From").  This information is
    considered public information, and it is a requirement of membership
    in USENET that this information be provided on request, either
    automatically in response to this control message, or manually, by
    mailing the requested information to the author of the message.
    This information is used to keep the map of USENET up to date, and
    to determine where netnews is sent.

    The format of the file mailed back to the author should be the same
    as that of the sys file.  This format has one line per neighboring
    host (plus one line for the local host), containing four colon
    separated fields.  The first field has the host name of the
    neighbor, the second field has a newsgroup pattern describing the
    newsgroups sent to the neighbor.  The third and fourth fields are
    not defined by this standard.  The sys file is not the same as the
    UUCP L.sys file.  A sample response is:

      From: cbosgd!mark  (Mark Horton)
      Date: Sun, 27 Mar 83 20:39:37 -0500
      Subject: response to your sendsys request
      To: mark@cbosgd.ATT.COM

      Responding-System: cbosgd.ATT.COM
      cbosgd:osg,cb,btl,bell,world,comp,sci,rec,talk,misc,news,soc,to,
  test
      ucbvax:world,comp,to.ucbvax:L:
      cbosg:world,comp,bell,btl,cb,osg,to.cbosg:F:/usr/spool/outnews
  /cbosg
      cbosgb:osg,to.cbosgb:F:/usr/spool/outnews/cbosgb
      sescent:world,comp,bell,btl,cb,to.sescent:F:/usr/spool/outnews
  /sescent
      npois:world,comp,bell,btl,ug,to.npois:F:/usr/spool/outnews/npois
      mhuxi:world,comp,bell,btl,ug,to.mhuxi:F:/usr/spool/outnews/mhuxi