# slack (margin)

A parameter whose window is narrower than the range allowed by what persists.

- Computed level: L18 (depth in the emergence graph, not abstraction)
- Status: review  ·  Domain: window  ·  Arena: general

## Emergence
**Emerges from:** [parameter](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-parameter.condition), [window](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-window.range), [persist](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-persist.continue), [allow](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-allow.permission), [narrow](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-narrow.spatial), [range](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-range.spatial)

**Through:** The condition of a persistent thing has a permitted range, but the functional window is constricted within it, creating a tighter bound than what persistence alone allows.

**Novel properties:**
- constriction relative to persistence
- tolerance below permitted range
- narrowing within allowance

## Examples
- The LHC maintains proton beam alignment within ±0.5mm despite thermal drift and ground motion. *(physics)*
- California's 2022 water allocation allowed 30% less than historical averages due to persistent drought. *(economics)*
- The ISS life support system recycles 93% of water, operating within 2°C of setpoint despite crew activity swings. *(engineering)*

## Used by
- [stretched thin](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-stretched-thin.capacity) (L19)

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*Canonical: https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-slack.margin*  
*Structured data: https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-slack.margin.json*  
*Every definition provably resolves to space, time, energy and pattern.*