This is the standard Bollinger Bands Width (BBW) indicator with the added capability of detecting the "Bollinger Bands Squeeze" as defined by John Bollinger:
The BBW squeeze happens when BBW < all BBWs of the past 125 intervals.
Whenever a BBW squeeze occurs, this means there is low volatility.
A low volatility period is almost always followed by high volatility: a large breakout (with price performing ample movement and exiting the BBW bands) may suddenly occur.
The breakout may be preceded by a fakeout, during which price moves in the opposite direction.
The BBW squeeze happens when BBW < all BBWs of the past 125 intervals.
Whenever a BBW squeeze occurs, this means there is low volatility.
A low volatility period is almost always followed by high volatility: a large breakout (with price performing ample movement and exiting the BBW bands) may suddenly occur.
The breakout may be preceded by a fakeout, during which price moves in the opposite direction.