Flow decomposition
Every order-book update the platform provides is decomposed exactly:
| Line | What it measures |
|---|---|
| Total Flow | Passive book changes + aggressive executions. The headline signal. |
| Passive Flow | Resting liquidity stacked (+) or pulled (−) across the nearest book levels. |
| Aggressive Flow | Executed volume delta (buys − sells), the classic tape delta. |
| Placement Flow | Passive Flow minus Aggressive Flow: orders placed and cancelled, with executions taken out. Hidden by default; see Placement Flow & the core line. |
Total Flow = Passive + Aggressive, exactly, on every event. There are not two rival formulas; there is one signal with two components. The aggressive component is the cumulative volume delta every order-flow trader already knows; the passive component is the stack/pull behaviour of the resting book.
Readings are never smoothed or filtered. The only redraws are ones you trigger by changing a setting; see changing the core line and switching modes.
Raw volume tells you what already traded. Flow shows what the order book is doing now: liquidity stacking up at a level, or quietly pulling away from it. It is context, not a forecast.
Depth: the headline signal measures the nearest levels per side, 10 by default (the Level Depth setting); a depth-1 variant of the same formula powers the deep-book warning.
The book itself is not flow. When an instrument's order book is first delivered (or re-delivered after a feed reconnect), the indicator treats that snapshot as the starting state rather than as stacking, so a book arriving as hundreds of individual inserts does not register as a burst of passive flow.
How the indicator reads Sierra Chart's data. It reads the order book each time Sierra Chart updates the chart (we recommend every 50 milliseconds; see getting started), up to 30 price levels per side or three times Level Depth if that is more. Each trade comes from Time & Sales, counted as a buy or a sell by the side the feed reports. The order book and the Time & Sales already on the chart when the study starts are not counted as flow. Off-exchange prints are not filtered out.
Next: the σ readout
Chart images. The chart images on this site show the indicator's display on market data, to explain what it draws. They are not trading results or trade recommendations, and the risk and hypothetical performance disclosures above apply to them. We publish no trading performance. The full text is on the disclosures page.