NTP (Time Server) and OSPi

This is more of a curiosity question but when it comes to timekeeping, when running on a Raspberry Pi, does OpenSprinkler use the system time for everything or a different clock? My thought is that it would use the system time and whatever tool you use for synchronizing time on the Pi is what is used. I maintain a couple GPS-linked NTP servers and generally use chrony for synchronizing time on all of my Linux-based devices. I noticed though, when looking at the JSON created when I export my settings, that there are settings for what looks like four different NTP servers but all have a value of zero; that is why I even question it.