Check for units in flag_masks and flag_values

[bertulus]

the cf-checker complains if no units is set for a variable with the flag_values attribute but not for a variable with the flag_masks attribute. Is this a mistake (around line 2314) or do I misunderstand the conventions here?

byte ancillary_instrument_status(station, ntime) ;
ancillary_instrument_status:flag_meanings = "low_battery ventilation_on" ;
ancillary_instrument_status:flag_masks = 1b, 2b ;
ancillary_instrument_status:long_name = "Instrument status" ;

byte ancillary_ta_flags(station, ntime) ;
ancillary_ta_flags:flag_meanings = "out_of_range very_warm" ;
ancillary_ta_flags:flag_values = 0b, 1b ;
ancillary_ta_flags:long_name = "Temperature flags" ;