o  filter in error

    The filters specified in the filters characteristic cannot be
    used for one of the following reasons:

    filters in      The named filters are already in use.
    use

    no such         The named filters do not exist.
    filters

 o  insufficient information

    One or more characteristics have not been specified.

    Arguments:

    reason      Indicates which characteristics have not been
                specified.

                DTE class    The DTE class characteristic has not
                             been specified.

                filters      The filters characteristic has not
                             been specified.