External references
Authoritative source material from outside OPDA — government departments, regulators, standards bodies. Captured locally because either the source was withdrawn (NTS) or it's important to have a snapshot for traceability.
NTS Material Information archive
The NTSELAT Material Information rules were withdrawn in late 2025 once
DMCC Act 2024 superseded the underlying Consumer Protection regulations.
We hold a recovered archive (mirrored from The Property Institute and
HousingLIN) at source/08-external-references/nts/.
The archive includes:
- NTS Material Information for Property Sales v1.0 (PDF)
- NTS Material Information for Property Lettings v1.0 (PDF)
- Quick Guide for Agents
- Quick Guide for Sellers
- Quick Guide for Buyers
- The original NTSELAT landing page mirror (showing the withdrawal notice)
These remain operationally relevant because (a) the nts.json overlay implements them, (b) MHCLG's
successor guidance is expected to be backwards-compatible, and (c) it's the
most-cited public material-information standard in the industry.
UK government pages
Captured at source/08-external-references/uk-government/.
| Page | Why it matters |
|---|---|
DPMSG founding announcement (Aug 2023) | The 14 founding members; the formal launch of DPMSG |
MHCLG Material Info consultation (Oct 2025) | The replacement-guidance consultation — outcome will shape nts.json |
Related W3C standards
OPDA's Trust Framework cites the following W3C specs as strategic alignment
partners. Local notes at source/08-external-references/related-w3c-specs/.
- W3C Verifiable Credentials Data Model 2.0
- W3C Decentralized Identifiers (DIDs) 1.0
- JSON Schema 2020-12 (the PDTF schemas use Draft-07)
- SKOS Core — used by our generated business glossary
- JSON-LD 1.1 — target serialisation for the linked-data layer
Other trust frameworks
Reference material from adjacent or precedent trust frameworks at
source/08-external-references/dcam/:
- EDM Council DCAM — Data Management Capability Assessment Model. OPDA's data-governance approach borrows the DCAM structure.
- Trust Over IP Foundation — the four-layer governance model PDTF follows. See ToIP governance.
- DIATF — UK Digital Identity and Attributes Trust Framework. Cited as a strategic alignment partner for identity-related claims.
Industry references
UK property forms archive— official PDFs of the BASPI, TA6, TA7, TA10, LPE1, FME1, CON29R, CON29DW, OC1, LLC1 formsRed Foundation — housing data report
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