It is often used to help traders determine how in-play a ticker is.
General rule of thumb is the higher the RVOL, the more in play a stock is.
I myself like to use it as a substitute of the indicator itself.
Relative Volume = Current / Average Volume
Any time there is a spike which causes a crossover of the user set 'Smoothed Moving Average' or 'Threshold' a green/red dot will appear at the top. The color of the dot is dependent on closing of the candle. Therefore it does not necessarily mean price will continue in that direction since spikes often happen in peaks or valleys.
The level at which custom alerts and signal can be set. The higher the value, the more required to trigger.
Built in Alerts:
You can set custom alerts for the crossovers of the adjustable threshold, or the average RVOL band.
that is the only one that does what i outlined in my comment. you have to disable extended session in order for it to work. use stocks and 5 day loop period to get the effect you want