Character vector with the same length as `x` indicating the type of object
each element in `x` is. Elements of this string are:
- Y
Year.
- M
Month, or minutes in the time part. When followed by a '.' in the
time part these are fractional minutes.
- D
Day, this can be dau of the month, day of the week or day of the year.
- T
Marks the start of the time part.
- H
Hour. When followed by a '.' these are fractional hours.
- M
Month.
- S
Seconds. When followed by a '.' these are fractional seconds.
- Z
Time is in GMT/Zulu time.
- ±Z
The time zone is indicated using an offset from GMT.
- P
A period. These are not parsed further.
- I
An interval. These are not parsed further.
- R
A repeating interval. These are not parsed further.