# legacy code (unmeasured)

a system whose parameter window no living maintainer has measured, still inside it, maintained without knowing where its walls are.

- Computed level: L15 (depth in the emergence graph, not abstraction)
- Status: review  ·  Domain: computer science  ·  Arena: software development

## Emergence
**Emerges from:** [window](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-window.range), [wall](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-wall.range-end), [parameter](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-parameter.condition), [maintenance](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-maintenance.upkeep), [drift](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-drift.aimless), [model](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-model.representation), [self-model](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-self-model.reflexive), [inside](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-inside.spatial), [know](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-know.cognitive), [live](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-live.biological), [measure](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-measure.quantitative), [measurement](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-measurement.quantitative), [still](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-still.quiet), [system](https://emergencemachine.com/tools/lexicon/what-is-the-meaning-of-system.organized)

**Through:** The interaction of maintenance, unmeasured boundaries, and the absence of a cognitive model of those boundaries allows the persistence of a system in ignorance of its own limits.

**Novel properties:**
- unmeasured persistence
- maintained ignorance
- precarious stability

## Examples
- The Therac-25 radiation therapy machine malfunctioned in 1985 due to unmeasured race conditions in code originally written in the 1970s. *(computing)*
- The New York City subway's signal system, largely unchanged since the 1940s, runs trains with timetables adjusted by hand-drawn chalk logs. *(engineering)*
- Farmers in the Sahel maintain irrigation ditches laid during French colonial rule, though no one recalls the original grading specifications. *(institutions)*

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