nformation,
        see C{_statefulUpdate}'s docstring.
    @type _STATEFUL_UPDATE: See C{_statefulUpdate}'s docstring
    @cvar _ACCEPTABLE_UNITS: A set of NMEA notations of units that are
        already acceptable (metric), and therefore don't need to be converted.
    @type _ACCEPTABLE_UNITS: C{frozenset} of bytestrings
    @cvar _UNIT_CONVERTERS: Mapping of NMEA notations of units that are not
        acceptable (not metric) to converters that take a quantity in that
        unit and produce a metric quantity.
    @type _UNIT_CONVERTERS: C{dict} of bytestrings to unary callables
    @cvar  _SPECIFIC_SENTENCE_FIXES: A mapping of sentece types to specific
        fixes that are required to extract useful information from data from
        those sentences.
    @type  _SPECIFIC_SENTENCE_FIXES: C{dict} of sentence types to callables
        that take self and modify it in-place
    @cvar _FIXERS: Set of unary callables that take an NMEAAdapter instance
        and extract useful data from the sentence data, usually modifying the
        adapter's sentence data in-place.
    @type _FIXERS: C{dict} of native strings to unary callables
    @ivar yearThreshold: The earliest possible year that data will be
        interpreted as. For example, if this value is C{1990}, an NMEA
        0183 two-digit year of "96" will be interpreted as 1996, and
        a two-digit year of "13" will be interpreted as 2013.
    @type yearThreshold: L{int}
    @ivar _state: The current internal state of the receiver.
    @type _state: C{dict}
    @ivar _sentenceData: The data present in the sentence currently being
        processed. Starts empty, is filled as the sentence is parsed.
    @type _sentenceData: C{dict}
    @ivar _receiver: The positioning receiver that will receive parsed data.
    @type _receiver: L{ipositioning.IPositioningReceiver}
    c