This is a structure, a value type and hence is not nullable. You can make a member or a variable of
nullable if you use the type
System.DateType? myTime = null;
if (myTime == null)
Please see: http://msdn.microsoft.com/en-us/library/1t3y8s4s%28v=vs.90%29.aspx
Semantically, it looks like you complement the value set of any non-nullable type with one extra point: null value, that's all. I don't advise to try to use "reset value" (like
). The default value is a valid point of time, it cannot be considered as "no time". Don't use it, better use the nullable type.