# Immutable Events

> The requirement that recorded events never change once written, only be appended to.

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

Listed in [Lexicon terms](https://banes-lab.com/api/records/lexicon.md), after [Events](https://banes-lab.com/records/lexicon/events.md) and before [Local Transaction](https://banes-lab.com/records/lexicon/local-transaction.md).

## Category

- [Event Messaging Async](https://banes-lab.com/records/lexicon-category/event-messaging-async.md)

## Required by

- [Append-Only Log](https://banes-lab.com/records/architecture/append-only-log.md)

## Linked from

- [Event / Messaging / Asynchronous Architecture](https://banes-lab.com/ontology/principles/architecture-category-event-messaging-asynchronous-architecture.md)