Open interest (OI) — the number of option contracts currently HELD open at each strike. Unlike volume (today's trading), OI is the standing position base — what people are actually holding.
Max pain — the strike that minimizes the total intrinsic value paid to option holders (where the most options expire worthless). Price tends to gravitate toward it into expiry, as dealers hedge toward the point that costs holders most.
OI walls — the biggest call-OI strike above spot (resistance) and put-OI strike below (support). Price often stalls at these. Raw-OI walls, distinct from gex's gamma-weighted walls.
Standing OI put/call — held puts ÷ held calls. The positioning of existing hedges/bets, separate from today's flow.
The call — max pain above spot → ↑ pull (stronger near expiry); below → ↓. Spot near the put wall = support (↑), near the call wall = resistance (↓). Feeds Oracle; weight set by Phase-3 calibration.