Volume Zone Oscillator (VZO) is an indicator that presents a different way of looking at OBV.
VZO is a difference (delta) between OBV and an exponential moving average.
The EMA becomes the baseline 0.
And in this way we can observe the strength of the movements, overbought and oversold (when the OBV is far from the average) and divergences.
Credits go to @NeoButane as basis is taken from his open-source code and I modified it - changes described below.
Positive -> bullish, negative -> bearish
-60/60 is seen as the limit of the oscillator range, and a pullback should be expected from there
-40/40 are in general Oversold/Overbought levels