static void set_PreserveNullString(bool preserveNullString);
This method takes a boolean value that sets a flag on the datasource indicating whether the NULL string values should be handled separate from 0 number values. The default behavior for the ToString() and FromString methods on the GeodeticPoint and ProjectedPoint classes is to handle empty string values as a 0. Since 0 is a valid position for some Northing and Easting values, this can create issues for GIS applications that use GeoCalc. This option allows the user to pass the string value "NULL" down to the string parsing methods, and have them handled as non-numeric values. This will allow the application to differentiate between a 0 coordinate and an empty coordinate string.
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