Returns a date/time secs seconds later than the stored date/time. Except when the instance is a local clock time (type ClockTime), the calculation is done in UTC to ensure that the result takes proper account of clock changes (e.g. daylight savings) in the time zone. The result is expressed using the same time specification as the original instance. Note that if the instance is a local clock time (type ClockTime), any daylight savings changes or time zone changes during the period will render the result inaccurate. If the instance is date-only, secs is rounded down to a whole number of days and that value is added to the date to find the result.
