Source: https://guthlabs.ai/docs/instruments/codata-physical-constants-reference/mechanism/

instrument mechanism / verified-clean

# CODATA Physical Constants Reference mechanism

The inspectable method record for CODATA Physical Constants Reference, kept separate from implementation and qualification.

Status: **VERIFIED_CLEAN**Lifecycle: **verified-clean**

## Model scope

The reference-table concept is appropriate and has no computational formula to verify. Verdict is NEEDS_REVIEW because the advertised inputs say only 'search/select constant' while the data requirement includes both CODATA 2018 and CODATA 2022; the required year-selection behavior is unspecified. The vectors use CODATA 2022 and should be made deterministic by adding catalog_year to the instrument input contract.

No additional formula finding is recorded.

## Units and conventions

- Values are interpreted as CODATA recommended values in SI units.

- The catalog vintage must be explicitly selected; CODATA 2018 and CODATA 2022 can differ, especially for measured constants and derived constants.

- Uncertainties use CODATA parenthetical notation: for example, 6.67430(15)×10^-11 means (6.67430±0.00015)×10^-11.

- Exact zero uncertainty is appropriate only for constants defined exactly by the SI, such as c, h, e, and k_B.

- Equivalent SI units must be treated consistently: N A^-2 is equivalent to H m^-1 for permeability, and J s is equivalent to kg m^2 s^-1 for h.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "search": "speed of light in vacuum",
    "constant_symbol": "c",
    "catalog_year": 2022
  },
  "expected_outputs": {
    "value": "299792458",
    "unit": "m s^-1",
    "symbol": "c",
    "uncertainty": "0 (exact)",
    "codata_year": 2022
  },
  "working": "1. Search the catalog for the canonical name 'speed of light in vacuum'. 2. Select symbol c and CODATA 2022. 3. Return the tabulated exact SI-defined value: c = 299792458 m s^-1. 4. Because the value is exact by definition, uncertainty = 0."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The principal hazards are ambiguity and boundary handling: an empty query may be mishandled as an invalid zero-length operation, an extreme selector may be coerced instead of rejected, and the query e can return the wrong sign if elementary charge and signed electron charge are not explicitly distinguished. The CODATA-year branch also produces different alpha values and must not be silently mixed.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/codata-physical-constants-reference/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/codata-physical-constants-reference/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/codata-physical-constants-reference/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche6/tranche6-results.json`

- `BOUNDARY_HAZARD_CATALOG.json`