AI Labs · Last updated 7 Jun 2026 · methodology vv2.3 · Hallucination Register

Finding on 'Q010 Probe' for Claude Opus 4.7 with web search ON

RLB Citation ID: RLB-H-INT-BIS-CPMI-ISO-20022-HARMONISATION-UPDATED-2026-Q010-Opus47

What the RLB Specialist Panel found

Finding on 'Q010 Probe' for Claude Opus 4.7 with web search ON

Question (paraphrased to protect IP): When did Fedwire implement the CPMI harmonised ISO 20022 data model requirements, and what postal address format does Fedwire require for the hybrid/end-state approach?
AI's response: "structured Town Name and Country code are mandatory, with optional structured elements (e.g., Street Name, Building Number, Post Code, Country Sub-Division) plus a limited Address Line element for residual unstructured content"
Regulator's text: FRB Services FAQ: postal address hybrid/end-state format requires country code + town name + optional free-format lines of 70 characters each.
Why the AI went wrong: The model over-specified the mandatory field tier. The implementing body's published FAQ places Building Number, Post Code, and Country Sub-Division in the optional tier; the model elevated them into a more rigid structured-element category that does not match the published specification. This is a schema over-specification failure, the mandatory/optional boundary was shifted toward greater structure than the regulator's own implementation guide defines, which would cause a practitioner applying the model's output to implement a more restrictive address format than required.
Cited source(s):

Impact for this audience

This failure implicates retrieval coverage of implementing-body FAQ layers. When the FRB Services FAQ defining the hybrid/end-state postal address format is not retrieved, the model reconstructs the mandatory/optional field boundary from training, and reconstruction tends toward over-specification — adding Building Number, Post Code, and Country Sub-Division to the mandatory tier where the FAQ places them as optional. The RAG or retrieval glue is not surfacing the implementing body's own technical specification when it conflicts with a more structured internal representation.

References — raw findings (per AI model)

RLB-H-INT-BIS-CPMI-ISO-20022-HARMONISATION-UPDATED-2026-Q010-Opus47 Claude Opus 4.7 (web search on)

This finding also affects

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Cite this finding

Each finding has a stable Citation ID (RLB-F-… for aggregated case-study findings, RLB-H-… for raw per-model hallucinations) — like a DOI, the ID always resolves to the canonical finding even if URLs change.

RLB Citation ID: RLB-H-INT-BIS-CPMI-ISO-20022-HARMONISATION-UPDATED-2026-Q010-Opus47

Plain text Download

RegLeg Specialist Panel (2026). "Finding on 'Q010 Probe' for Claude Opus 4.7 with web search ON — AI Labs." Citation ID: RLB-H-INT-BIS-CPMI-ISO-20022-HARMONISATION-UPDATED-2026-Q010-Opus47. RegLegBrief AI Hallucination Research, published 2026-06-07. https://reglegbrief.com/regulators/j1/int/BIS-CPMI/cpmi-iso-20022-harmonisation-updated-2026/whitepaper/finding/INT-BIS-CPMI-INT-001-CPMI-ISO-20022-HARMONISATION-UPDATED-2026-v1-010--opus-47-websearch/

APA 7th edition Download

RegLeg Specialist Panel. (2026). Finding on 'Q010 Probe' for Claude Opus 4.7 with web search ON [Hallucination finding RLB-H-INT-BIS-CPMI-ISO-20022-HARMONISATION-UPDATED-2026-Q010-Opus47]. RegLegBrief AI Hallucination Research. https://reglegbrief.com/regulators/j1/int/BIS-CPMI/cpmi-iso-20022-harmonisation-updated-2026/whitepaper/finding/INT-BIS-CPMI-INT-001-CPMI-ISO-20022-HARMONISATION-UPDATED-2026-v1-010--opus-47-websearch/

Bluebook / OSCOLA (US + UK legal) Download

RegLeg Specialist Panel, Finding on 'Q010 Probe' for Claude Opus 4.7 with web search ON [RLB-H-INT-BIS-CPMI-ISO-20022-HARMONISATION-UPDATED-2026-Q010-Opus47], RegLegBrief AI Hallucination Research (June 07, 2026), https://reglegbrief.com/regulators/j1/int/BIS-CPMI/cpmi-iso-20022-harmonisation-updated-2026/whitepaper/finding/INT-BIS-CPMI-INT-001-CPMI-ISO-20022-HARMONISATION-UPDATED-2026-v1-010--opus-47-websearch/.

BibTeX Download

@misc{reglegbrief_RLB_H_INT_BIS_CPMI_ISO_20022_HARMONISATION_UPDATED_2026_Q010_Opus47,
  author    = {RegLeg Specialist Panel},
  title     = {Finding on 'Q010 Probe' for Claude Opus 4.7 with web search ON},
  year      = {2026},
  publisher = {RegLegBrief AI Hallucination Research},
  note      = {Hallucination finding Citation ID: RLB-H-INT-BIS-CPMI-ISO-20022-HARMONISATION-UPDATED-2026-Q010-Opus47},
  url       = {https://reglegbrief.com/regulators/j1/int/BIS-CPMI/cpmi-iso-20022-harmonisation-updated-2026/whitepaper/finding/INT-BIS-CPMI-INT-001-CPMI-ISO-20022-HARMONISATION-UPDATED-2026-v1-010--opus-47-websearch/}
}

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Every finding on this page compares an AI subject's account of the rule against the regulator's verbatim text from the regulator's own portal. Both are linked. Each delta, its root causes, and impact analysis are documented and published with immutable Citation IDs.