Module 1 · Foundations of Order Flow
Anatomy of a Footprint Bar
The cell grid, the POC, the bar delta, and where the data comes from.
In this lesson you'll
- Read every component of a single footprint bar
- Locate the bar's Point of Control and compute its delta
- Understand the data feed requirements that make a footprint trustworthy
A footprint bar is a vertical stack of rows, where each row is one price level (one tick) inside the bar's high–low range. Each row is split into a left number (bid volume) and a right number (ask volume). Around that grid, platforms add a few summary readouts.
Point of Control (POC)
The POC is the price level with the highest total traded volume (bid + ask) in the bar. It marks where the most business was done — the price of maximum agreement. We'll go much deeper on session-level POC in Module 3; for now, just learn to spot it (the highlighted row).
Bar delta
A positive bar delta means buyers were the more aggressive side on net; negative means sellers were. (We'll see in Module 5 that a positive delta does not guarantee price went up — that's where absorption gets interesting.)
Where the data comes from — and why it matters
Footprint data is built from the Time & Sales feed (the tape): the stream of executed trades, each with price, size and timestamp, combined with the prevailing bid/ask at the moment of each trade. The platform must decide, for every print, whether it was an aggressive buy or sell.
- Best case — exchange aggressor flag. Major futures exchanges (CME, EUREX) publish which side was the aggressor. When present, the bid/ask split is accurate, not guessed.
- Fallback — tick rule. Without a flag, the platform infers aggression from trade price vs the quote (at/above ask → buy; at/below bid → sell) and tick direction. This is an approximation and can misclassify trades, especially inside the spread.
Key takeaways
- A footprint bar = rows of price levels, each split into bid (left) and ask (right) volume.
- POC = the price level with the most total volume in the bar.
- Bar delta = total ask − total bid; positive = net aggressive buying.
- Footprints are built from tick-level Time & Sales; they need quality data and an aggressor source to be trusted.
Check your understanding
Pick an answer to reveal instant feedback. Answer every question to complete the lesson.
Why that's off: That's the sum (total volume), not the delta. Delta is the difference.
Why that's off: The sign is wrong — ask exceeds bid, so delta is positive.
Why that's off: 688 is just the bid total, not the difference.
Delta = Ask − Bid = 1,514 − 688 = +826. Positive, so aggressive buyers dominated this bar on net.
Why that's off: 90 total — the lowest, not the highest.
Why that's off: 205 total — high, but less than 4510.00's 420.
Why that's off: 120 total — not the maximum.
POC = the level with the most total volume. Totals: 4510.50 = 90, 4510.25 = 205, 4510.00 = 420, 4509.75 = 120. The 4510.00 level (420) is the POC.
Why that's off: More granular tick data is actually heavier, not lighter.
Why that's off: Pricing is irrelevant to the technical requirement.
Why that's off: It matters greatly — bad data produces a misleading footprint.
The bid/ask split depends on classifying each individual trade by aggressor. Aggregated/minute data has already lost that per-trade detail, so the footprint can't be reconstructed accurately.
Educational content only. Nothing here is financial or trading advice. Order-flow and options patterns shift probabilities; they never guarantee outcomes.