John Ehlers is known for making a lot of new tools for technical analysis. Here is one more.
According to Ehlres:
Even though he tends to over praise his work, we can agree with some of the statements he makes, and this indicator is by all means one of the useful tools in the code base collection that we are building here for all of the traders.
This version of Zone Trade indicator is made to show as histogram in separate window.Zone Trade
The indicator was described by B. Williams as fourth dimension - Trading Zone.