+DI indicates the bullish component of the historical series movement and is normally used in conjunction with the other W.Wilder indicators, namely ADX and -DI.
The interpretative theory also establishes the following rules:
In the case of ADX and +DI with increasing trends against a declining movement of the -DI the system expresses the intensification of a bullish trend;
if the ADX has a lateral or slightly decreasing trend, while +DI and -DI tend to a sort of convergence, the system shows the start of a congestion phase: