case 0: string="average"; break;
    case 1: string="accumulation"; break;
    case 2: string="maximum"; break;
    case 3: string="minimum"; break;
    case 4: string="difference (value at the end of the time range minus value at the beginning)"; break;
    case 5: string="root mean square"; break;
    case 6: string="standard deviation"; break;
    case 7: string="covariance (temporal variance)"; break;
    case 8: string="difference ( value at the beginning of the time range minus value at the end)"; break;
    case 9: string="ratio"; break;
    case 51: string="climatological mean value"; break;
    case 192: string="climatological mean value"; break;
    case 193: string="average of n forecasts (or initialized analyses); each product has forecast period of p1 (p1=0 for initialized analyses); products have reference times at intervals of p2, beginning at the given reference time."; break;
    case 194: string="average of forecast accumulations. p1 = start of accumulation period. p2 = end of accumulation period. reference time is the start time of the first forecast, other forecasts at 24-hour intervals. number in ave = number of forecasts used."; break;
    case 195: string="average of successive forecast accumulations. p1 = start of accumulation period. p2 = end of accumulation period. reference time is the start time of the first forecast, other forecasts at (p2 - p1) intervals. number in ave = number of forecasts used"; break;
    case 196: string="average of forecast averages. p1 = start of averaging period. p2 = end of averaging period. reference time is the start time of the first forecast, other forecasts at 24-hour intervals. number in ave = number of forecast used"; break;
    case 197: string="average of successive forecast averages. p1 = start of averaging period. p2 = end of averaging period. reference time is the start time of the first forecast, other forecasts at (p2 - p1) intervals. number in ave = number of forecasts used"; break;
    case 198: string="climatological average of n analyses, each a year apart, starting from initial time r and for the period from r+p1 to r+p2."; break;
    case 199: string="climatological average of n forecasts, each a year apart, starting from initial time r and for the period from r+p1 to r+p2."; break;
    case 200: string="climatological root mean square difference between n forecasts and their verifying analyses, each a year apart, starting with initial time r and for the period from r+p1 to r+p2."; break;
    case 201: string="climatological standard deviation of n forecasts from the mean of the same n forecasts, for forecasts one year apart. the first forecast starts wtih initial time r and is for the period from r+p1 to r+p2."; break;
    case 202: string="climatological standard deviation of n analyses from the mean of the same n analyses, for analyses one year apart. the first analyses is valid for  period r+p1 to r+p2."; break;
    case 203: string="average of forecast accumulations. p1 = start of accumulation period. p2 = end of accumulation period. reference time is the start time of the first forecast, other forecasts at 6-hour intervals. number in ave = number of forecast used"; break;
    case 204: string="average of forecast averages. p1 = start of averaging period. p2 = end of averaging period. reference time is the start time of the first forecast, other forecasts at 6-hour intervals. number in ave = number of forecast used"; break;
    case 205: string="average of forecast accumulations. p1 = start of accumulation period. p2 = end of accumulation period. reference time is the start time of the first forecast, other forecasts at 12-hour intervals. number in ave = number of forecast used"; break;
    case 206: string="average of forecast averages. p1 = start of averaging period. p2 = end of averaging period. reference time is the start time of the first forecast, other forecasts at 12-hour intervals. number in ave = number of forecast used"; break;
    case 255: string="missing"; break;