# Schema

## GET /collections/{collectionId}/schema

> Get schema for a single OS NGD feature collection

```json
{"openapi":"3.0.1","info":{"title":"OS NGD API – Features","version":"v1.8.0"},"tags":[{"name":"Collections","description":"Retrieve information about collections"}],"servers":[{"url":"https://api.os.uk/features/ngd/ofa/v1"}],"paths":{"/collections/{collectionId}/schema":{"get":{"tags":["Collections"],"summary":"Get schema for a single OS NGD feature collection","operationId":"getSchema","parameters":[{"name":"collectionId","in":"path","description":"A known collection ID.","required":true,"schema":{"type":"string","enum":["asu-gbpcd-postcodeunitarea-1","asu-gbpcd-postcodeunitpoint-1","bld-fts-building-1","bld-fts-building-2","bld-fts-building-3","bld-fts-building-4","bld-fts-buildingaccesslocation-1","bld-fts-buildingline-1","bld-fts-buildingpart-1","bld-fts-buildingpart-2","gnm-fts-crowdsourcednamepoint-1","gnm-fts-namedarea-1","gnm-fts-namedpoint-1","gnm-fts-namedroadjunction-1","lnd-fts-land-1","lnd-fts-land-2","lnd-fts-land-3","lnd-fts-landform-1","lnd-fts-landformline-1","lnd-fts-landformpoint-1","lnd-fts-landpoint-1","lus-fts-site-1","lus-fts-site-2","lus-fts-siteaccesslocation-1","lus-fts-siteaccesslocation-2","lus-fts-siteroutingpoint-1","str-fts-compoundstructure-1","str-fts-compoundstructure-2","str-fts-compoundstructure-3","str-fts-fieldboundary-1","str-fts-structure-1","str-fts-structure-2","str-fts-structure-3","str-fts-structureline-1","str-fts-structurepoint-1","trn-fts-cartographicraildetail-1","trn-fts-rail-1","trn-fts-rail-2","trn-fts-rail-3","trn-fts-roadline-1","trn-fts-roadtrackorpath-1","trn-fts-roadtrackorpath-2","trn-fts-roadtrackorpath-3","trn-fts-streetlight-1","trn-ntwk-buslane-1","trn-ntwk-connectinglink-1","trn-ntwk-connectingnode-1","trn-ntwk-cyclelane-1","trn-ntwk-ferrylink-1","trn-ntwk-ferrynode-1","trn-ntwk-ferryterminal-1","trn-ntwk-path-1","trn-ntwk-pathlink-1","trn-ntwk-pathlink-2","trn-ntwk-pathlink-3","trn-ntwk-pathnode-1","trn-ntwk-pavementlink-1","trn-ntwk-railwaylink-1","trn-ntwk-railwaylinkset-1","trn-ntwk-railwaynode-1","trn-ntwk-road-1","trn-ntwk-roadjunction-1","trn-ntwk-roadlink-1","trn-ntwk-roadlink-2","trn-ntwk-roadlink-3","trn-ntwk-roadlink-4","trn-ntwk-roadlink-5","trn-ntwk-roadnode-1","trn-ntwk-street-1","trn-ntwk-tramonroad-1","trn-rami-averageandindicativespeed-1","trn-rami-highwaydedication-1","trn-rami-maintenancearea-1","trn-rami-maintenanceline-1","trn-rami-maintenancepoint-1","trn-rami-reinstatementarea-1","trn-rami-reinstatementline-1","trn-rami-reinstatementpoint-1","trn-rami-restriction-1","trn-rami-routinghazard-1","trn-rami-routingstructure-1","trn-rami-specialdesignationarea-1","trn-rami-specialdesignationline-1","trn-rami-specialdesignationpoint-1","wtr-fts-intertidalline-1","wtr-fts-tidalboundary-1","wtr-fts-water-1","wtr-fts-water-2","wtr-fts-water-3","wtr-fts-waterpoint-1","wtr-ntwk-waterlink-1","wtr-ntwk-waterlink-2","wtr-ntwk-waterlinkset-1","wtr-ntwk-waternode-1"]}}],"responses":{"200":{"description":"Schema for an Ordnance Survey National Geographic Database feature collection.","content":{"*/*":{"schema":{"type":"object","additionalProperties":{"type":"object"}}}}},"400":{"description":"The schema request is not supported. Please refer to documentation for examples."},"404":{"description":"Collection '{collectionId}' is not a supported Collection. Please refer to the documentation for a list of supported Collections."},"405":{"description":"The HTTP method requested is not supported. This endpoint only supports 'GET' requests."},"406":{"description":"A request header value was not supported."}}}}}}
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.os.uk/os-apis/accessing-os-apis/os-ngd-api-features/technical-specification/schema.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.