A pun between the word flag and the adjective flagging (less dynamic), this indicator have two bands who react faster when in contact to the price. Imagine you are under sheets, if you abruptly rise, the sheets will instantaneously go up, then if you abruptly get down, the sheets will fall slowly until being in contact with a surface, this is because of a type of friction called drag or air resistance, this force is described in fluid dynamics and i inspired myself from that for the creation of the indicator.
The indicator
The indicator is made of two bands, one upper band and one lower band, then a weighted average of each bands, this average is weighted depending on which band the price is closer. The length control the period of the indicator, in general higher lengths will create wider bands, you must consider that this parameter behave differently than other ones and may create slower results in comparison with other bands indicators while having the same length period.
The indicator can use a simple breakout methodology (see trailing stop part) but can sometime provide support and resistance points, in fact i believe that when the average variability/volatility of band A is higher than the average variability/volatility of band B and that the price cross band B then price will reverse its direction, this claim is not justified, research is needed.
Trailing Stop Mod
It is possible to make the indicator act as a trailing stop, in order to do so just tick the trailing stop mod box.
The average/bands will automatically disappear being replaced by the trailing stop.
Conclusion
I was just playing around when making the skeleton of the indicator, i hope the code is easy to understand, if you need some kind of explanation just pm me, i'm always open to help people/receive suggestions.