ADR-0013: A Chemical Record is keyed on its SDS document, not on a substance

Status: Accepted — amends ADR-0004, which otherwise stands Date: 2026-09-02

Decisions

D-18 A Chemical Record is created from one SDS and identified by product name, supplier and revision date

CAS Number becomes an optional identifier that pure substances happen to carry, not the primary key.

D-19 Identification reads CAS Number when the label shows one, and falls back to product name

ADR-0004's preference order is unchanged; only the guarantee that a CAS exists is withdrawn.

Context

R-25: the plant's actual process chemicals include น้ำยาล้างชิ้นงาน, a formulated parts-cleaning solution. CAS registers substances, not blends, so this product has a trade name and a supplier and no CAS number at all. R-11 had made CAS the primary key and ADR-0004 had made it the identification target — both were derived from Acetone, a pure substance, and generalised from a sample of one.

In an automotive parts plant, formulated cleaners, degreasers, coolants, adhesives and coatings are likely the majority of what is on the floor. Pure reagents belong to a laboratory's world, not a production line's. Keying on the SDS document also matches how the plant's own binder is organised, because a plant buys products rather than substances.

Rejected options

• A dual model of substances and products, with products listing their hazardous component substances — the most faithful to chemistry, and it would enable component-level reasoning. Rejected as roughly doubling the data model for a prototype (D-01).
• Pure substances only, mixtures out of scope — rejected: it would exclude a chemical the source explicitly names, and probably most of what is actually on the plant floor.

This ruling may not be re-decided

If a change contradicts this ADR: stop and raise it. Do not implement over it. Do not reintroduce CAS as a required field because it makes matching easier — the mixtures that lack one are the common case, not the exception.

Consequences

Product-name matching is fuzzier than CAS matching, so manual search becomes more load-bearing than ADR-0004 anticipated. Revision date being part of identity means two revisions of the same product are two records, which is correct — and it gives the staleness signal D-06's sync needs.

Coverage

Upstream	Landed in	Evidence	Note
R-29	D-19	the revised caption "label or QR code" confirms the read order
R-11	D-18	CAS demoted to optional; the record is keyed on the SDS document	corrects ADR-0004's landing, which asserted CAS as the identifier