How dates, times, and durations should be represented in the output. This is ignored if value_render_option is FORMATTED_VALUE. The default dateTime render option is SERIAL_NUMBER.
public enum DateTimeRenderOptionEnum
Instructs date, time, datetime, and duration fields to be output as strings in their given number format (which depends on the spreadsheet locale).
Instructs date, time, datetime, and duration fields to be output as doubles in "serial number" format, as popularized by Lotus 1-2-3. The whole number portion of the value (left of the decimal) counts the days since December 30th 1899. The fractional portion (right of the decimal) counts the time as a fraction of the day. For example, January 1st 1900 at noon would be 2.5, 2 because it's 2 days after December 30th 1899, and .5 because noon is half a day. February 1st 1900 at 3pm would be 33.625. This correctly treats the year 1900 as not a leap year.