Public Sub SetGYear(ByVal iYear As Long)
  Property Description  
    Argument iYear sets the Year part of the date. (Valid Range -9999 to 9999)  
    Description Populates this DateTime as type gYear.  
    Remarks NOTE: DateTime uses the XML Schema formula for proleptic Gregorian calendar where year 0 is illegal and -4 (4BC) as a leap year.
Throws: on parsing invalid values.
Throws: if this DateTimes current type is not either zeroYear or gYear.