I found the following on the NMEA website
regarding standards and years that various ones were used. My GUESS would be that if the version is unspecified it was probably the first (0180 from 1980). The person at BW was referring to the fact that any device which accepts NMEA 0183 will communicate with the Garmin. Below is from NMEA website:The NMEA program that is perhaps best known to the general maritime public is the standards program. It was Dr. Robert Freeman who was responsible for much of the early work on standards.As an autopilot manufacturer, his initial motivation was to create a link that would allow lorans to communicate with his products. This lead to the 1980 codification known as 0180. Revisions in 1982 and ’83 became the 0182 and 0183 standards respectively.0183 has undergone a continued refinement and evolution since its inception, but the hardware and software parameters have remained largely unchanged. As more manufacturers began to see the value of adhering to a standard series of interface codes, the 0183 started to become the worldwide standard for marine electronics.BTW the current 0183 is the 3.0 version and being replaced by 2000 with which it is hoped all marine eletronics from all manufacturers will be able to interface. Instead of propriatary standards like Seatalk, everybody will talk the same langauge, so too speak.