Buy - OBV is trending upward
Sell - OBV is trending downward
Parameters available:
t - the number of periods that OBV has been trending
Slope - the minimum slope of the moving average of OBV when it is trending
MA period - the number of periods used for the period of the moving average of the OBV
Rule type - please refer to 140 for details
Data type - please refer to 141 for details