# Derivation Period

> A formal definition of how often a derivation edge runs, on every read, between stores or once at creation, which decides whether a copy is stale or is a record.

Record: `lexicon:derivation-period`
Kind: artifact
Layer: [Execution Core](https://banes-lab.com/records/layer/execution-core.md)
Canonical: https://banes-lab.com/ontology/lexicon#lexicon-derivation-period

Listed in [Lexicon terms](https://banes-lab.com/api/records/lexicon.md), after [Distinguished Copy](https://banes-lab.com/records/lexicon/distinguished-copy.md) and before [Carrier Field](https://banes-lab.com/records/lexicon/carrier-field.md).

## Category

- [Coordination Surfaces](https://banes-lab.com/records/lexicon-category/coordination-surfaces.md)

## Required by

- [Period-Decided Disposition](https://banes-lab.com/records/architecture/period-decided-disposition.md)

## Linked from

- [Coordination Surfaces](https://banes-lab.com/ontology/principles/architecture-category-coordination-surfaces.md)
- [Coordination Surfaces](https://banes-lab.com/ontology/lexicon/lexicon-category-coordination-surfaces.md)

## Evidence in the code

- [models/coordination.model.md](https://banes-lab.com/source/coordination/models/coordination.model.md.md)