help/opers/user

   1 USER <username> <unused> <unused> :<real name/gecos>
   2
   3 USER is used during registration to set your gecos
   4 and to set your username if the server cannot get
   5 a valid ident response.  The second and third fields
   6 are not used, but there must be something in them.
   7 The reason is backwards compatibility