//----------------------------------------------------------------------
   // RplFunction used by the Rules to do some data conversion on objects

   int ConvertStorageToArea(
          double stor, double storScale, const char* storUnits, 
          double* area, double areaScale, const char* areaUnits, 
          const Date_Time* dateTime=NULL, const DeltaTime* step=NULL);

   int ConvertStorageToAreaAtDate(
          double stor, double storScale, const char* storUnits, 
          double* area, double areaScale, const char* areaUnits, 
          const Date_Time* dateTime, const DeltaTime* step);

   int ConvertElevationToArea (
          double elev, double elevScale, const char* elevUnits, 
          double* area, double areaScale, const char* areaUnits,
          const Date_Time* dateTime=NULL, const DeltaTime* step=NULL);

   int ConvertElevationToAreaAtDate (
          double elev, double elevScale, const char* elevUnits, 
          double* area, double areaScale, const char* areaUnits,
          const Date_Time* dateTime, const DeltaTime* step);

   int ConvertElevationToStorage (
          double elev, double elevScale, const char* elevUnits, 
          double* stor, double storageScale, const char* storageUnits,
          const Date_Time* dateTime=NULL, const DeltaTime* step=NULL);

   int ConvertElevationToStorageAtDate (
          double elev, double elevScale, const char* elevUnits, 
          double* stor, double storageScale, const char* storageUnits,
          const Date_Time* dateTime, const DeltaTime* step);

   int ConvertStorageToElevation (
          double stor, double storScale, const char* storUnits, 
          double* elev, double elevScale, const char* elevUnits,
          const Date_Time* dateTime=NULL, const DeltaTime* step=NULL);

   int ConvertStorageToElevationAtDate (
          double stor, double storScale, const char* storUnits, 
          double* elev, double elevScale, const char* elevUnits,
          const Date_Time* dateTime, const DeltaTime* step);

   int ConvertElevationToMaxRegulatedSpill (
          double elev, double elevScale, const char* elevUnits,
          double* ruleSpill, double spillScale, const char* spillUnits, 
          const Date_Time* dateTime=NULL, const DeltaTime* step=NULL);

   int ConvertElevationToUnregulatedSpill (
          double elev, double elevScale, const char* elevUnits,
          double* ruleSpill, double spillScale, const char* spillUnits, 
          const Date_Time* dateTime=NULL, const DeltaTime* step=NULL);
   
   int RulesConvert (TableSlot* table, 
     int fromColumn, double fromValue, double fromScale, const char* fromUnits, 
     int toColumn, double* toValue, double toScale, const  char* toUnits, 
     const Date_Time* dateTime, const DeltaTime* step);

   int Convert (
          double fromValue, double fromScale, const char* fromUnits, 
          double* toValue,  double toScale,   const char* toUnits, 
          const Date_Time* dateTime, const DeltaTime* step=NULL);

   int Convert (
          double fromValue, double fromScale, unit_type fromUnitType, 
          double* toValue,  double toScale,   unit_type toUnitType, 
          const Date_Time* dateTime, const DeltaTime* step=NULL);