[This is preliminary documentation and is subject to change.]
Get the date time format string to be used by "ToDateString()" for date-time formatting.


- showDate (Boolean)
- Specifies true to include the date in the date-time string.
- showWeekDay (Boolean)
- Specifies true to include the weekday in the date-time string.
- showTime (Boolean)
- Specifies true to include the time in the date-time string.
- fraction (Int32)
- Specifies the number of decimal places for fraction of second display (max. 7).

Returns the date-time format string.