Generally, at bottoms the rectangle is long and flat and at blow off tops it is tall and narrow. The fact that no one has noticed or written about this phenomenon is rather amazing. Until the invention of personal computers the task of adding up daily or even weekly volume numbers was a very difficult task. I think it is likely that some professionals have used these ideas but have kept them as part of their trading secrets. I like to think of the floating supply of shares as the missing piece to the price and volume puzzle.
Stocks trade in relation to the number of shares actually available for trading.
Without the float a price and volume chart is only two-thirds of the puzzle. A. Float numbers for all companies are found at a variety of public sources including Edgar Online and Yahoo Finance. You'll find the float number at the bottom left of the Profile page. And why are they not included in software packages like TradeStation and MetaStock. The mainstream technical analysis community is only slowly realizing the power of these indicators and what they show.