# Stable Element Hierarchy

> The requirement that the set of element types stay fixed so new operations can be added over them.

Record: `lexicon:stable-element-hierarchy`
Kind: constraint
Layer: [Design Patterns Core](https://banes-lab.com/records/layer/design-patterns-core.md)
Canonical: https://banes-lab.com/ontology/lexicon#lexicon-stable-element-hierarchy

Listed in [Lexicon terms](https://banes-lab.com/api/records/lexicon.md), after [Stable Algorithm Skeleton](https://banes-lab.com/records/lexicon/stable-algorithm-skeleton.md) and before [Subject/Subscriber Contract](https://banes-lab.com/records/lexicon/subject-subscriber-contract.md).

## Category

- [Behavioral Patterns](https://banes-lab.com/records/lexicon-category/behavioral-patterns.md)

## Required by

- [Visitor Pattern](https://banes-lab.com/records/architecture/visitor-pattern.md)

## Linked from

- [Behavioral Patterns](https://banes-lab.com/ontology/principles/architecture-category-behavioral-patterns.md)