DMS ↔ Decimal Degrees mechanism

Model scope

The specification is ambiguous because it claims bidirectional conversion but supplies only a forward formula, and it does not define negative-coordinate conventions, accepted DMS syntax, normalization, or rounding. The blank honest_label should explicitly state that this is an angular-format converter, not a datum transformation, coordinate-reference-system conversion, or geodetic position calculation.

• The supplied formula only converts DMS to decimal degrees; no decimal-degrees-to-DMS formula is provided, despite the instrument claiming bidirectional conversion.
• For negative coordinates, `dd = d + m/60 + s/3600` is ambiguous and is incorrect if only the degrees component carries the negative sign. The standard signed interpretation is `dd = sign(d) * (abs(d) + m/60 + s/3600)` when minutes and seconds are nonnegative.
• DMS parsing syntax is unspecified: degree, minute, and second separators; whitespace; hemisphere suffixes; and whether signed minutes or seconds are accepted are all ambiguous.
• Valid-component constraints are missing. Standard normalized DMS requires 0 <= minutes < 60 and 0 <= seconds < 60, with degree sign or hemisphere carrying the sign.
• Decimal-to-DMS rounding, precision, and carry behavior are unspecified, including cases where rounded seconds become 60 or minutes become 60.

Units and conventions

• Degrees, minutes, and seconds are angular subdivisions: 1 degree = 60 minutes and 1 minute = 60 seconds.
• `m/60` and `s/3600` are degree quantities, so the output decimal value is in degrees.
• The test DMS values use nonnegative minutes and seconds; a negative coordinate applies its sign to the complete angular magnitude.
• Decimal-degree inputs are numeric angular values in degrees, not radians.
• The reverse conversion test assumes normalized output formatted as signed degrees-minutes-seconds with seconds allowed to contain a decimal fraction.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "dms": "40°26′46″"
  },
  "expected_outputs": {
    "decimal_degrees": 40.44611111111111
  },
  "working": "40 + 26/60 + 46/3600 = 40 + 0.4333333333333333 + 0.0127777777777778 = 40.44611111111111°"
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

The extreme-magnitude vector exposes loss of the one-second fractional component when JavaScript Number arithmetic adds 1/3600 to 100000000000000000000. The negative-DMS vector also exposes an output-changing convention ambiguity unless the sign convention is explicitly defined.

Other records

Sources and evidence

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

• VERIFIED_LEDGER.json
• evidence-tranche4/tranche4-results.json
• BOUNDARY_HAZARD_CATALOG.json