> ## Documentation Index > Fetch the complete documentation index at: https://offthepace.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Key Concepts: the vocabulary used throughout these docs > A high-level orientation to pace delta, the seven decomposition terms, the tyre cliff, and structural pace as used throughout the Off The Pace docs and app. A handful of ideas recur on every page and every chart in the app. This page defines them at a glance; it does not derive them. For the full formula behind any term, see the [Transform tab](/decomposition/seven-term-identity); for a precise, column-level definition of every term, see the [Glossary](/reference/glossary). Sign convention is consistent everywhere in Off The Pace: **negative is faster** (shown in green), **positive is slower** (shown in red). ## Pace delta `pace_delta` is how fast a driver is relative to the field on a given lap not the raw lap time. A driver running at exactly the field's typical pace has `pace_delta ≈ 0`. This normalisation is what lets you compare a residual at Monaco directly against one at Monza, even though the two circuits' lap times differ by 20+ seconds. ## The seven components Every lap's `pace_delta` is split into seven named pieces that sum to it exactly: **fuel**, **compound** (tyre wear), **rubber** (track evolution), **ambient** (temperature), **constructor** (the car), **dirty air** (aero wake), and **driver skill** (everything else). See the [Transform tab](/decomposition/seven-term-identity) for the full equations and what each term captures. ## The tyre cliff The lap at which a tyre compound's grip falls off sharply tyre wear before the cliff is gradual; after it, pace loss steepens fast. The app's [Tyre Cliff Survival](https://off-the-pace.web.app/tyre-strategy/survival) feature and [Degradation Simulator](https://off-the-pace.web.app/ml/simulator) both surface this onset point, fitted historically and predicted live by the ML models. ## Clean lap A lap eligible for fitting the physics terms not the first lap, not a pit-in/out lap, not under Safety Car or VSC, not wet, not flagged as a data-quality anomaly. Dirty laps would bias every coefficient downstream, so they're excluded before any term is estimated. ## Structural pace / ghost car A constructor's or driver's pace with the confounds removed e.g. a driver's speed independent of the car, or a car's speed independent of the driver. The app's [Ghost Race Standings](https://off-the-pace.web.app/ghost-car/standings) feature re-runs every result with this structural pace in equal machinery, answering "who would have won in the same car?" ## Stint and compound A **stint** is the set of consecutive laps a driver runs on one set of tyres between pit stops. A **compound** is the tyre type (Soft, Medium, Hard, Intermediate, Wet) each with its own degradation curve and cliff onset, stored per circuit and season. ## Where the depth lives Every equation, every coefficient, the CI-enforced identity. Precise, column-level definitions for every term. How the cliff and degradation predictions are trained and validated.