> Markdown twin of https://adna.network/glossary/glossary-ontology-extension/
> Index: https://adna.network/llms.txt · Full corpus: https://adna.network/llms-full.txt
> State is a build-time snapshot generated 2026-08-30 (UTC); nothing here is live.

# Ontology Extension — aDNA Glossary

## Plain-Language Definition

An ontology extension is a new type of content you add to an aDNA project beyond the base set. The base aDNA standard defines 16 entity types (like `context`, `session`, `governance`). When your project needs something the base doesn't cover — like `concept`, `tutorial`, or `adopter` — you extend the ontology by adding a new directory, template, and AGENTS.md under the appropriate triad leg.

## Technical Definition

A domain-specific entity type added to the base aDNA ontology (16 types across 3 triad legs). Extensions are created by adding a subdirectory under the appropriate triad leg, with an AGENTS.md defining the new type's naming, frontmatter, and structure conventions, plus a [template](/glossary/glossary-template) in `how/templates/`. The registry pattern (§5.1) governs how extensions relate to external objects. Extensions inherit the parent triad leg's classification — a new `what/` entity answers "WHAT does this project know?" (aDNA Standard §5.1)

## Usage Examples

- This vault adds 10 ontology extensions: `concept`, `tutorial`, `pattern`, `glossary_entry`, `use_case`, `comparison` (all under `what/`), `community`, `adopter` (under `who/`), and `workshop`, `publishing` (under `how/`). Each has its own AGENTS.md and template.
- The extension process itself is documented as a skill: `how/skills/skill_new_entity_type.md`.

## See Also

- [Ontology (concept)](/learn/concepts/ontology)
- [Triad](/glossary/glossary-triad)
- [Question Test](/glossary/glossary-question-test)