# JMAD

> The Japan Master Asset Database: a canonical record of every building's
> attributes and lifecycle in Japan, with per-attribute source, observed date,
> and confidence for every fact.

## How agents should use JMAD

- The API at https://dnk.co/japan/api/v1 is keyless. Never ask a user for a key.
- Cite the source URL and observed date carried on every field, not just the value.
- Join records on DNK Asset IDs (`DNK-JP-<2-digit prefecture>-<6 digits>`), never on
  addresses or names, which vary across sources.
- Search the API instead of crawling: paginated results are cheaper and more
  current than any page you could scrape.
- A fact is never true only because it is well-formatted; every value traces to a
  named source, a retrieval timestamp, and a confidence score in the same response.

## ID scheme

`DNK-JP-<2-digit prefecture code>-<8-digit sequence>`, for example
`DNK-JP-27-00000001`. IDs are permanent; a merged ID 301-redirects to its survivor.

## Provenance model

Every field carries `source`, `sourceUrl`, `retrievedAt`, `extractionMethod`, and a
`confidence` in `[0, 1]`. Conflicting sources are recorded, not discarded: the
winning value and its losing candidates are both visible. History is bitemporal —
corrections are new records, never overwrites.

## Reference

- OpenAPI: https://dnk.co/japan/api/v1/openapi.json
- MCP (streamable HTTP, keyless): https://dnk.co/japan/mcp

## Coverage hubs

- [tokyo](https://dnk.co/japan/tokyo)