https://en.wikipedia.org/wiki/Standard_time
But this is still different to a time someone enters into a calendar. Standard time can change its offset (to UTC) over time (e.g. DST), while a time in a calendar is fixed in the nominal sense.
"scientific datetime" is quite ambiguous, since I would consider science-level precision time to be TAI (International Atomic Time, what UTC uses as a reference), or maybe UT1, which is one variant of UT (Universal Time, unrelated to UTC), depending on the scientific field. For simple cases, UTC might be enough, so you could call this "UTC".
I think practically what matters for developers are three things:
- Standard time (dependent on timezone)
- UTC (the reference for standard times in the different timezones)
- Calendar times (seems to be called "floating time" [0]), just referring to a specific date and time, usually independent from both standard time and UTC, from the author's perspective (others viewing a foreign calendar might see times interpreted in their own timezone). Often scoped by physical location, but not necessarily.