It is a very old version of High/Low indicator (basically the idea comes from a Gann High Low activator with some modifications).
Modification was made at that time to allow users to use the indicator in scalping but as well in trending mode.
Usage is simple :


SAR trading v2.0
Trading signals are generated based on a comparison of two trend indicators: iMA (Moving Average, MA) and iSAR (Parabolic SAR). The EA works on the zero bar, only one position can be open. Trailing stop is used.
DojiTrader
The Expert Advisor trades using the "Japanese Doji Candlestick" pattern.