anchor.diff:     (
         l_access_class
         | l_exec_timeout
  +      | l_length
         | l_login
         | l_null
         | l_transport
  
positive.code: l_exec_timeout
  :
     EXEC_TIMEOUT minutes = DEC seconds = DEC? NEWLINE
  ;
  
  l_login
  
negative.code:       | FLUSH_AT_ACTIVATION
        | HISTORY
        | IPV6
        | LOCATION
        | LOGGING
        | LOGOUT_WARNING
  