@GETDATE[[date][,title]] : Display a calendar dialog and returns the selected date in yyyy-mm-dd format.
You can optionally pass a default date (also in yyyy-mm-dd format). If you do not specify a default date, @GETDATE will use the current date.
You can also optionally pass a default title, which will replace the default "Date" in the title bar.
Example:
echo %@getdate[]
