Im doing a fetch to get a date from a database in java (the date should always be
Z stands for the zero UTC offset.
If the time is in UTC, add a Z directly after the time without a space.
Z is the zone designator for the zero UTC offset.
"09:30 UTC" is therefore represented as "09:30Z" or "0930Z", while "14:45:15 UTC" would be "14:45:15Z" or "144515Z".
The portion immediately before the
Z translates into fraction of second; here,
From your question above,
00:00:00.588 means "about a half second past midnight", with the last three digits after the period,
588, translating: milliseconds.
... more details here on (ISO 8601 standard).