# Query Model

> **Status:** Informational. Not normative. Future specification planned.

HEXT is a Semantic Object Graph. Future query interfaces SHOULD operate on graph semantics, not on XML tree paths.

This document describes intended query concepts only. It does not define syntax, semantics, or conformance requirements.

## Design Intent

XPath addresses XML trees. HEXT queries address **relationships among semantic nodes**.

A future HEXT Query language MAY express questions such as:

```
SELECT Object
WHERE depends_on = "RFC-NVS74"
```

```
FIND Evidence
WHERE provenance.primary_generator = "human"
  AND object.type = "document.rfc"
```

```
MATCH (a:Object)-[:derived_from]->(b:Object)
WHERE a.lifecycle = "draft"
```

## Query Dimensions

Future queries MAY traverse:

| Dimension | Example |
|---|---|
| Object identity | `object.id`, `object.type`, `object.lifecycle` |
| Relationships | `derived_from`, `registry_ref`, `observation_ref` |
| Provenance | contributors, agency, human_touch |
| Integrity | seal age, ledger step count, hash validity |
| Evidence | format, content signatures |
| External links | observation registry coordinates |

## Non-Goals

This informational model explicitly excludes:

- XPath or XQuery as the primary query interface
- SQL-style table projections of XML elements
- Observation Plane runtime queries (Layer 7 responsibility)
- Mandatory server-side query APIs in HEXT Core

## Relationship to Other Graph Models

HEXT MAY serve as a common foundation for future graph layers:

- Knowledge Graph
- Semantic Graph
- Trust Graph
- Observation Graph

Query specifications for those layers are out of scope for HEXT Core v2.2.0.

## Future Work

A dedicated query specification RFC is expected to define:

- Graph query syntax
- Relationship type registry
- Result serialization (likely JSON projection)
- Indexing and registry integration

See [ROADMAP.md](../ROADMAP.md).