A label to identify the source bus, eg serial-COM1, eth-local,etc . Can be anything but should follow a predicatable format
OptionalaisAIS Message Type
OptionalcanNMEA2000 can name of the source device
OptionalinstanceNMEA2000 instance value of the source message
OptionalpgnNMEA2000 pgn of the source message
OptionalsentenceSentence type of the source NMEA0183 sentence, $GP[RMC],092750.000,A,5321.6802,N,00630.3372,W,0.02,31.66,280511,,,A*43
OptionalsrcNMEA2000 src value or any similar value for encapsulating the original source of the data
OptionaltalkerTalker id of the source NMEA0183 sentence, $[GP]RMC,092750.000,A,5321.6802,N,00630.3372,W,0.02,31.66,280511,,,A*43
OptionaltypeA human name to identify the type. NMEA0183, NMEA2000, signalk
Source of data in delta format, a record of where the data was received from. An object containing at least the properties defined in 'properties', but can contain anything beyond that.