"C/N" meaning in All languages combined

{
  "forms": [
    {
      "form": "N",
      "tags": [
        "canonical"
      ]
    },
    {
      "form": "Ns",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "N (plural Ns)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "word": "credit note"
        }
      ],
      "categories": [
        {
          "_dis": "96 4",
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w+disamb"
        },
        {
          "_dis": "97 3",
          "kind": "other",
          "name": "Pages with 1 entry",
          "parents": [],
          "source": "w+disamb"
        },
        {
          "_dis": "99 1",
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w+disamb"
        }
      ],
      "glosses": [
        "Initialism of credit note."
      ],
      "id": "en-C/N-en-noun-W~vK-P6a",
      "links": [
        [
          "credit note",
          "credit note#English"
        ]
      ],
      "tags": [
        "abbreviation",
        "alt-of",
        "initialism"
      ]
    },
    {
      "glosses": [
        "construction number (aircraft construction)."
      ],
      "id": "en-C/N-en-noun-IHQ36HDt"
    }
  ],
  "word": "C/N"
}

{
  "categories": [
    "English abbreviations",
    "English countable nouns",
    "English entries with incorrect language header",
    "English lemmas",
    "English nouns",
    "English words without vowels",
    "Pages with 1 entry",
    "Pages with entries"
  ],
  "forms": [
    {
      "form": "N",
      "tags": [
        "canonical"
      ]
    },
    {
      "form": "Ns",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "N (plural Ns)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "alt_of": [
        {
          "word": "credit note"
        }
      ],
      "categories": [
        "English initialisms"
      ],
      "glosses": [
        "Initialism of credit note."
      ],
      "links": [
        [
          "credit note",
          "credit note#English"
        ]
      ],
      "tags": [
        "abbreviation",
        "alt-of",
        "initialism"
      ]
    },
    {
      "glosses": [
        "construction number (aircraft construction)."
      ]
    }
  ],
  "word": "C/N"
}