This is an indicator described by Larry Williams in one of his books. Larry won the 1987 World Cup Championship of Futures Trading, where he turned $10,000 to over $1,100,000 in a 12-month competition with real money.
Larry used this indicator to track divergences between price action and volume, which he called patterns of accumulation (bullish divergence) and distribution(bearish divergence). Its logic is similar to On Balance Volume(OBV), where it accumulates up and down volume in a single line, but also takes into account the size of the candle in its calculation, by taking the difference between the open and close, and the high and the low.
Enjoy!