Flags for Causal Factors

Hi, experts

when setting up forecast tree, there are flags for causal factor, such as short, long, Multiplicative Group 1,Multiplicative Group 2. Although the implementation guide have some sample explain, could anyone give a clear explaination on the effects on those flags, such as the difference between short and long, if choose short for causal factor, how it will impact system generated forecast, thanks a lot