void ParseISO8601Date(string xsdDate)
  Property Description  
    Argument xsdDate valid XML Schema date  
    Description Populates this XmlDateTime with the value specified as a valid XML ISO8601 date, gDay, gMonth, gYear, gMonthDay or gYearMonth.  
    Remarks A valid date (see ISO 8601 standard). where the parts in [...] are optional.
A valid date comprises [-]CCYY-MM-DD[[Z]|[[+|-]hh:mm]]
A valid gDay comprises ---DD[[Z]|[[+|-]hh:mm]]
A valid gMonth comprises --MM[[Z]|[[+|-]hh:mm]]
A valid gYear comprises [-]CCYY[[Z]|[[+|-]hh:mm]]
A valid gMonthDay comprises --MM-DD[[Z]|[[+|-]hh:mm]]
A valid gYearMonth comprises [-]CCYY-MM[[Z]|[[+|-]hh:mm]]
where the parts in [...] are optional.

Throws: LtInvalidValueException thrown on parsing invalid values.
See: ParseISO8601Date(std::string)
See: ParseISO8601Time(std::string)