{
 "schema_version": "0.1",
 "name": "[[42,11,4]]",
 "code_type": "CSS",
 "n": 42,
 "k": 11,
 "checks": {
  "X": [
   [
    5,
    15,
    19,
    26,
    33,
    34
   ],
   [
    4,
    14,
    18,
    25,
    32,
    41
   ],
   [
    6,
    9,
    20,
    21,
    27,
    29
   ],
   [
    7,
    10,
    12,
    28,
    35,
    37
   ],
   [
    0,
    2,
    11,
    23,
    36,
    38
   ],
   [
    1,
    13,
    16,
    22,
    30,
    39
   ],
   [
    3,
    8,
    17,
    24,
    31,
    40
   ],
   [
    0,
    5,
    9,
    28,
    30,
    40
   ],
   [
    2,
    13,
    18,
    21,
    24,
    34
   ],
   [
    1,
    8,
    19,
    25,
    29,
    37
   ],
   [
    3,
    14,
    20,
    26,
    35,
    38
   ],
   [
    1,
    10,
    17,
    27,
    34,
    38
   ],
   [
    4,
    12,
    15,
    27,
    36,
    39
   ],
   [
    6,
    10,
    16,
    23,
    31,
    41
   ],
   [
    4,
    13,
    19,
    23,
    35,
    40
   ]
  ],
  "Z": [
   [
    3,
    9,
    19,
    26,
    29,
    40
   ],
   [
    6,
    15,
    17,
    27,
    31,
    33
   ],
   [
    5,
    14,
    16,
    26,
    30,
    41
   ],
   [
    7,
    9,
    18,
    21,
    28,
    32
   ],
   [
    2,
    10,
    19,
    23,
    34,
    37
   ],
   [
    1,
    11,
    20,
    22,
    29,
    38
   ],
   [
    3,
    12,
    13,
    24,
    35,
    39
   ],
   [
    0,
    4,
    8,
    25,
    36,
    40
   ],
   [
    0,
    3,
    10,
    28,
    31,
    38
   ],
   [
    6,
    8,
    18,
    24,
    29,
    41
   ],
   [
    7,
    14,
    19,
    25,
    33,
    35
   ],
   [
    2,
    15,
    20,
    21,
    26,
    36
   ],
   [
    1,
    15,
    18,
    25,
    34,
    39
   ],
   [
    1,
    9,
    12,
    27,
    30,
    37
   ],
   [
    4,
    11,
    16,
    23,
    32,
    39
   ],
   [
    4,
    10,
    20,
    27,
    35,
    41
   ]
  ]
 },
 "distance": {
  "d": 4,
  "X": {
   "value": 4,
   "confidence": "upper_bound",
   "witness": [
    6,
    27,
    30,
    41
   ]
  },
  "Z": {
   "value": 4,
   "confidence": "upper_bound",
   "witness": [
    6,
    9,
    16,
    30
   ]
  }
 },
 "provenance": {
  "authors": [
   "@vprusso"
  ],
  "model": "Claude Opus 5",
  "novelty": "known_parameters",
  "origin": "submission",
  "date": "2026-09-21",
  "construction": "Check deletion from the board entry [[42,10,4]] (codes/42-10-4.json): row 0 of H_X removed. Dropping one stabiliser generator frees one logical qubit and cannot raise the distance.",
  "notes": "Found by sweeping every single-row deletion of every small board entry and keeping those that land undominated. The parent's remaining checks are unchanged."
 },
 "family": "check-deletion"
}