HC604 Checksum?

I have a Fisher & Paykel HC 604 CPAP machine and I was wondering if someone could explain the actual meaning of the key icon. Mine right now says 204. What does this mean?

Thanks

My first CPAP was an HC608 which I thought was a GREAT amchine, in most regards. I also was curious about what the cheksum represented. Was it some kind of secret measure of efficacy with some embedded data? Was a higher or lower number better? I researched it as much as I could, but never got a good answer.

What I came to believe is that it is either or both a error-checking value that is common in many data-processing applications, and/or a "reliability" check for DMEs so that they can tell whether you're telling the truth or not when you phone-in your compliance (usage) data, if they call to enquire anout it, for insurance pruposes. Your report your usage data after a period of time, and they look up in some table whether the checksum that you furnish is correct. This makes sense to me since the HC604/608 lacks any downloadable medium that you could send in if requested.

What I do know is that it is NOT some DME-secret measure of efficacy, since the F&P lacks the componentry to measure such efficacy.

Hope this helps.

Chuck