---
title: Glossary
description: Definitions of Engine resources, retrieval, permissions, and completion.
doc_version: 0.1.0-preview
last_updated: 2026-09-14
---

# Glossary

Definitions of the terms used in Graphon Engine requests, responses, and guides. Follow each link for examples and the full contract.

## Resources

| Term | Definition |
| --- | --- |
| [Cluster](/engine/concepts/clusters) | One Engine deployment, with one base URL, a major API version, and a set of capabilities. |
| [Namespace](/engine/concepts/clusters) | A named tenant isolation boundary containing collections. Its name is unique in the cluster. |
| Tenant | An application customer or data owner isolated from other customers. A namespace provides that boundary. |
| [Collection](/engine/concepts/collections) | A named set of files that Search and Query address together. |
| [File](/engine/concepts/files) | A content resource in a collection with an ID, logical path, source, metadata, and processing status. |
| [Path](/engine/concepts/files#path-rules) | A case-sensitive UTF-8 file name inside a collection, beginning with a slash. |
| Prefix | The beginning of a path. A prefix ending with a slash selects a directory-like set of paths. |
| Source | The content input for a file: inline text, an upload, or a supported storage URI. |
| Metadata | A JSON object of application facts attached to a file. Metadata fields can be used in retrieval filters. |
| Resource ID | An immutable public identifier, such as ns_, col_, fil_, key_, job_, evt_, or acr_ with a ULID suffix. |

## Retrieval

| Term | Definition |
| --- | --- |
| [Search](/engine/concepts/retrieval) | An operation that returns ranked files or passages with evidence. |
| [Query](/engine/guides/query) | An operation that returns a natural-language answer grounded in one collection, with optional sources. |
| Evidence | Supporting text and an optional source location, such as a page, character span, or media time. |
| Citation | An answer marker such as [[SRC:0001]] that maps to a source entry keyed by [SRC:0001]. |
| Processing profile | The collection’s keyword, semantic, and graph flags. |
| Index generation | An opaque identifier for indexed content used by a retrieval request. |
| Filter | A typed condition that selects application data. A filter does not authorize a reader. |
| Cursor | An opaque continuation token returned by a list or Search response. |

## Access and completion

| Term | Definition |
| --- | --- |
| [API key](/engine/concepts/keys) | A secret credential that authenticates a program. Engine key secrets begin with gek_. |
| Scope | The cluster, namespace, or named collections that a key can reach. |
| Action | A permitted operation category: read, write, search, or query. |
| [Principal](/engine/concepts/access) | An exact user or group string supplied by the trusted application, such as user:u_8812. |
| Access rule | A list of readers allowed to retrieve content at a folder prefix or file path. |
| Governing rule | The single rule that decides whether a reader can retrieve a file. |
| Sealed rule | A folder rule that governs all descendants and overrides rules below it. |
| [Job](/engine/concepts/jobs) | The public record of an operation that continues after the request response. |
| Event | A status-change notification for a job, file, or collection. |
| Events webhook | A configured HTTP receiver for signed event deliveries from Engine. |
| Idempotency key | A caller-chosen request header that identifies one logical write for safe replay. |

Continue with [Concepts](/engine/concepts) or the complete [Get started walkthrough](/engine/get-started).
## Sitemap

See the full [sitemap](/sitemap.md) for all pages.