adjust_dtc: Add or Subtract Time from a Date-Time Object
In rpkyle/cscmisc: Miscellaneous Data Manipulation and Simulation Tools

Computes difftime for date-time objects in R, removing separators from CDISC-typical character strings as needed.

1	adjust_dtc(time1, timediff, units, tz, POSIX)

`time1`	Date-time object in character format.
`timediff`	Value by which to increment or decrement.
`units`	Units of `timediff`; i.e. minutes, hours, days or weeks.
`tz`	POSIX-compliant time zone.
`POSIX`	Boolean; if `TRUE`, output POSIXct object, otherwise output character string.