How to get DateNull in axapta X++

Hi,
DateNull for the date can be checked by two ways
1.Global::DateNull()
2.or like this

 if (endDate != mkdate(1,1,1900)

The minimum value for the date in x++ is 1/1/1900 and max value is 12/31/2154

If you have utcDateTime here is how you can set dateNull and maximum value

todayDate = DateTimeUtil::minValue();
maximumDate =  DateTimeUtil::maxValue();
blankUtcDate = utcDateTimeNull();