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        "cell": [
          6,
          3
        ],
        "gridResidualM": 3209.364324080859,
        "diagnosticResidualM": 3253.93274559037
      },
      {
        "role": "withheld",
        "sourcePixel": [
          568.5538024902344,
          115.74439239501953
        ],
        "sentinelPixel": [
          3.0317797660827637,
          380.4689025878906
        ],
        "cell": [
          10,
          2
        ],
        "gridResidualM": 6871.974257625476,
        "diagnosticResidualM": 6905.781365357596
      },
      {
        "role": "withheld",
        "sourcePixel": [
          303.8768615722656,
          156.1285858154297
        ],
        "sentinelPixel": [
          340.6382141113281,
          164.93272399902344
        ],
        "cell": [
          3,
          3
        ],
        "gridResidualM": 2809.4067754845078,
        "diagnosticResidualM": 2847.9488190093134
      }
    ],
    "interpretation": "14 of17 spatially withheld descriptor matches agree with diagnostic fit within3px. Three false matches are retained in the register and excluded from the visual-control subset. This is algorithmic matching, not surveyed control."
  },
  "geographicCrosschecks": [
    {
      "kind": "independent Sentinel imagery",
      "item": "S2C_33KWR_20260930_0_L2A",
      "finding": "Distributed basemap texture/drainage correspondences support printed-grid placement; annotated geology not used as positional control. Visual comparison confirms broad drainage/ridge fabric; three false descriptor matches remain explicitly recorded."
    }
  ],
  "limitations": [
    "Source symbol digitisation \u00b13px (~42m) is separate from grid/scale reading and unknown datum error.",
    "Withheld matching residuals describe image agreement, not surveyed collar accuracy.",
    "Scale-bar endpoint reading can create systematic scale error.",
    "Issuer basemap acquisition date unknown. Sentinel acquisition 2026-09-30.",
    "Alternative datum remains unconfirmed; no empirical shift or diagnostic correction applied.",
    "VB05/VB06 individual identities remain unresolved. RC27/RC28 remain unlocated."
  ],
  "independentSurveyControls": 0,
  "cutoff": "2026-09-30"
}