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    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 Captured locally because either the source was withdrawn (NTS) or it's important to have a snapshot for traceability.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    The NTSELAT Material Information rules were withdrawn in late 2025 once DMCC Act 2024 superseded the underlying Consumer Protection regulations.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/.

    PageWhy 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

    Construction and BIM property dictionaries

    Candidate modelling reference — not an OPDA requirement

    ISO 23386:2020 is a published International Standard for describing, authoring and maintaining construction data properties and groups of properties in interconnected data dictionaries. Here, property means an attribute or characteristic described in a data dictionary, not a real-estate asset. The standard defines a method and governance expectations; it does not provide the dictionary's domain content.

    ReferenceAuthority and statusWhy it matters to OPDAOPDA treatment
    ISO 23386:2020
    Building information modelling and other digital processes used in construction — methodology to describe, author and maintain properties in interconnected data dictionaries     		ISO; edition 1, published March 2020 and confirmed current following its 2025 review. Provides a reference method for data-property definitions, property metadata, expert review, change requests, governance and mappings between data dictionaries. This is directly relevant to OPDA's glossary, data-dictionary and controlled-vocabulary work. Record as evidence for the relevant domain working groups and as a candidate modelling-method reference. Do not import it wholesale or treat it as an OPDA conformance requirement without an explicit review and decision.

    Stakeholder context: OPDA has been advised that NLIS (Land Data) is working to this standard for property construction data. That relationship is useful discovery evidence and should be confirmed directly with NLIS before it is recorded as a formal dependency or commitment.

    The catalogue records the official reference and OPDA's assessment only. The paid ISO publication has not been copied into the OPDA resource archive.

    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/.

    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.
    • DVSTF — UK Digital Verification Services Trust Framework (the rename of the former DIATF). Cited as a strategic alignment partner for identity-related claims.

    Industry references

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