I'm searching for an r command that will notify me if I create a time that
does not exist due to Daylight Savings Time. For example, if I run the
following command on a windows machine

> ISOdatetime(2010,03,14,2,10,0, tz = "") # My system time is set to the
United States Central Time Zone
[1] NA

R returns NA, which is the behavior I want. However, if I run the same
command on a mac, R returns a POSIXct object and I have to examine the
object manually to notice that I had tried to create an impossible time.

ISOdatetime(2010,03,14,2,10,0, tz = "")
[1] "2010-03-14 01:10:00 CST"

Is there a method of creating time objects in R that will always return NA
for non-existant times, no matter the operating system?

Thank you sincerely,
Garrett

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