Source: https://guthlabs.ai/docs/instruments/coordinate-format-converter-multi/mechanism/

instrument mechanism / verified-clean

# Coordinate Format Converter (multi) mechanism

The inspectable method record for Coordinate Format Converter (multi), kept separate from implementation and qualification.

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

## Model scope

The claimed multi-format conversion is standard in principle, but the provided formula description is insufficient to verify correctness. The exact unresolved ambiguity is the MGRS-to-decimal point convention and precision policy; additional unresolved behavior includes UTM zone-boundary/antimeridian handling, special Norway/Svalbard zones, input grammar, and datum declaration. Verdict is NEEDS_REVIEW until these are specified and implemented against authoritative WGS84/MGRS test data.

- The specification only says "chained coordinate transforms" and does not define the actual WGS84 geographic-to-UTM and UTM-to-geographic equations, longitude-zone rule, latitude-band rule, MGRS 100 km-square tables, or precision/truncation behavior.

- The implementation must distinguish UTM hemisphere from the MGRS latitude-band letter; these are not interchangeable labels.

- UTM requires zone selection as floor((longitude + 180) / 6) + 1, with the standard Norway and Svalbard zone exceptions if global coverage is claimed.

- MGRS conversion requires the correct zone-dependent easting-letter sequence and odd/even-zone northing-letter sequence, including omitted letters I and O.

- MGRS is a finite-precision grid reference, not an exact point. The specification does not state whether conversion to decimal uses the southwest corner, cell center, or an interval.

- The specification does not state whether longitude is normalized to [-180,180), how antimeridian coordinates are handled, or whether coordinates exactly on a UTM zone boundary use the eastern or western zone.

## Units and conventions

- Decimal latitude and longitude are in degrees, not radians.

- DMS components are degrees, arcminutes, and arcseconds; 1 degree = 60 arcminutes and 1 arcminute = 60 arcseconds.

- Latitude is positive north and longitude is positive east; S and W hemisphere suffixes negate the corresponding signed value.

- UTM uses WGS84 ellipsoid parameters a = 6378137 m and inverse flattening 298.257223563, central scale factor k0 = 0.9996, false easting 500000 m, and false northing 0 m in the northern hemisphere or 10000000 m in the southern hemisphere.

- UTM easting and northing are in metres.

- The MGRS examples use 5 digits for easting and northing, giving 1 m nominal precision.

## Inspectable vector

One of 4 source-bound review vectors:

````
{
  "inputs": {
    "format": "decimal",
    "latitude_deg": 40,
    "longitude_deg": -105
  },
  "expected_outputs": {
    "decimal": {
      "latitude_deg": 40,
      "longitude_deg": -105
    },
    "dms": "40°00'00.000\\\"N, 105°00'00.000\\\"W",
    "utm": {
      "zone": 13,
      "hemisphere": "N",
      "easting_m": 500000,
      "northing_m": 4427757.219
    },
    "mgrs": "13T EE 00000 27757"
  },
  "working": "DMS: 40 + 0/60 + 0/3600 = 40°N; -(105 + 0/60 + 0/3600) = -105°E. UTM zone = floor((-105 + 180)/6) + 1 = floor(12.5) + 1 = 13. Zone 13 central meridian = 6(13) - 183 = -105°. Therefore longitude difference is 0°, so the transverse-Mercator easting is the false easting 500000.000 m. Applying the WGS84 meridional-arc equation at latitude 40° gives northing 4427757.219 m. The 100 km easting square is E (500000 m), and the 4,400,000 m northing row in odd zone 13 is E; the 27,757 m remainder gives 27757. Hence MGRS = 13T EE 00000 27757."
}
````

## Failure boundary

**BREAK_CLAIMED** · SELF_FLAGGED

The specification leaves zone-boundary ownership, UTM pole rejection, MGRS precision, and directional sign conventions unspecified. A converter that silently accepts the pole or interprets unsigned longitude differently can produce undefined or materially different outputs.

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/coordinate-format-converter-multi/>)[03**Implementation**](<https://guthlabs.ai/docs/instruments/coordinate-format-converter-multi/implementation/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/coordinate-format-converter-multi/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`