CosmosTime.ZoneTime.ToString() - osexpert/CosmosTime GitHub Wiki
Iso format:
{time}+|-{offset}[{iana}]
{utc_time}Z[{iana}]
Examples:
2020-01-20T04:05:06.007+01:00[Europe/Berlin]
2020-01-20T04:05:06.007Z[Etc/UTC]
Time is variable length (milliseconds)
public override string ToString();