Date-time must be a POSIXct, POSIXlt, Date, Period, chron, yearmon, yearqtr, zoo, zooreg, timeDate, xts, its, ti, jul, timeSeries, and fts objects.
Examples
x <- ymd("2012-03-26")
minute(x)
#> [1] 0
minute(x) <- 1
minute(x) <- 61
minute(x) > 2
#> [1] FALSE