usr.sbin/sendmail/cf/KEY

   1
   2 Macro                                   Class
   3 -----                                   -----
   4 A       Internet relay                  --
   5 B       BITNET relay                    --
   6 C       CSNET relay                     --
   7 D       domain name
   8 I       --                              "Fake" (Internal) domains, i.e.
   9                                         UUCP, BITNET, CSNET.
  10 N       --                              hosts registered with the NIC
  11 R       UUCP relay host                 --
  12 U       This host's UUCP name           UUCP aliases
  13 V       None                            List of our UUCP neighbors
  14 W       Host to forward to for $=W      UUCP hosts on $W
  15 X       Host to forward to for $=X      UUCP hosts on $X
  16 Y       Host to forward to for $=Y      UUCP hosts on $Y