Clarification on certain fields in chronyc subcommands

Hello,

I'm trying to understand what "estimated error" means in the context of
`chronyc sources -v`. For example, we see `-308ns[ -582ns] +/-   17us` for
one of our sources. Does that mean that even though our recent offsets have
been in the order of ns, the actual error is close to microseconds?

Secondly, `chronyc sourcestats` says that our offset for a particular
source is always in the order of ns. Is that based on the offset between
the system clock and stratum-1 clock (thereby, including root dispersion
and root delay), or, between the system clock and the last sample that we
got back from our NTP server?


Thanks,
Abhijith