"A2" meaning in Norwegian Bokmål

{
  "etymology_text": "See the Wikipedia article ISO 216, the international standard on paper sizes.",
  "head_templates": [
    {
      "args": {
        "1": "nb",
        "2": "noun"
      },
      "expansion": "A2",
      "name": "head"
    }
  ],
  "hyphenation": [
    "A‧2"
  ],
  "lang": "Norwegian Bokmål",
  "lang_code": "nb",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "Norwegian Bokmål entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with 2 entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Pages with entries",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "nb",
          "name": "Paper sizes",
          "orig": "nb:Paper sizes",
          "parents": [
            "Paper",
            "Materials",
            "Manufacturing",
            "Human activity",
            "Human behaviour",
            "Human",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "examples": [
        {
          "text": "dimensions: 594 x 420 mm"
        }
      ],
      "glosses": [
        "A standard paper size, defined by ISO 216."
      ],
      "id": "en-A2-nb-noun-3nMxgVOa",
      "links": [
        [
          "paper",
          "paper"
        ]
      ],
      "related": [
        {
          "sense": "A paper sizes",
          "word": "2A0"
        },
        {
          "sense": "A paper sizes",
          "word": "A0"
        },
        {
          "sense": "A paper sizes",
          "word": "A1"
        },
        {
          "sense": "A paper sizes",
          "word": "A3"
        },
        {
          "sense": "A paper sizes",
          "word": "A4"
        },
        {
          "sense": "A paper sizes",
          "word": "A5"
        },
        {
          "sense": "A paper sizes",
          "word": "A6"
        },
        {
          "sense": "A paper sizes",
          "word": "A7"
        },
        {
          "sense": "A paper sizes",
          "word": "A8"
        },
        {
          "sense": "A paper sizes",
          "word": "A9"
        },
        {
          "sense": "A paper sizes",
          "word": "A10"
        }
      ],
      "tags": [
        "uncountable"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/ˈɑːtuː/"
    },
    {
      "audio": "NB - Pronunciation of Norwegian Bokmål «A2».ogg",
      "mp3_url": "https://upload.wikimedia.org/wikipedia/commons/transcoded/0/01/NB_-_Pronunciation_of_Norwegian_Bokm%C3%A5l_%C2%ABA2%C2%BB.ogg/NB_-_Pronunciation_of_Norwegian_Bokm%C3%A5l_%C2%ABA2%C2%BB.ogg.mp3",
      "ogg_url": "https://upload.wikimedia.org/wikipedia/commons/0/01/NB_-_Pronunciation_of_Norwegian_Bokm%C3%A5l_%C2%ABA2%C2%BB.ogg"
    },
    {
      "rhymes": "-uː"
    }
  ],
  "word": "A2"
}

{
  "etymology_text": "See the Wikipedia article ISO 216, the international standard on paper sizes.",
  "head_templates": [
    {
      "args": {
        "1": "nb",
        "2": "noun"
      },
      "expansion": "A2",
      "name": "head"
    }
  ],
  "hyphenation": [
    "A‧2"
  ],
  "lang": "Norwegian Bokmål",
  "lang_code": "nb",
  "pos": "noun",
  "related": [
    {
      "sense": "A paper sizes",
      "word": "2A0"
    },
    {
      "sense": "A paper sizes",
      "word": "A0"
    },
    {
      "sense": "A paper sizes",
      "word": "A1"
    },
    {
      "sense": "A paper sizes",
      "word": "A3"
    },
    {
      "sense": "A paper sizes",
      "word": "A4"
    },
    {
      "sense": "A paper sizes",
      "word": "A5"
    },
    {
      "sense": "A paper sizes",
      "word": "A6"
    },
    {
      "sense": "A paper sizes",
      "word": "A7"
    },
    {
      "sense": "A paper sizes",
      "word": "A8"
    },
    {
      "sense": "A paper sizes",
      "word": "A9"
    },
    {
      "sense": "A paper sizes",
      "word": "A10"
    }
  ],
  "senses": [
    {
      "categories": [
        "Norwegian Bokmål entries with incorrect language header",
        "Norwegian Bokmål lemmas",
        "Norwegian Bokmål nouns",
        "Norwegian Bokmål terms spelled with numbers",
        "Norwegian Bokmål uncountable nouns",
        "Pages with 2 entries",
        "Pages with entries",
        "Rhymes:Norwegian Bokmål/uː",
        "nb:Paper sizes"
      ],
      "examples": [
        {
          "text": "dimensions: 594 x 420 mm"
        }
      ],
      "glosses": [
        "A standard paper size, defined by ISO 216."
      ],
      "links": [
        [
          "paper",
          "paper"
        ]
      ],
      "tags": [
        "uncountable"
      ]
    }
  ],
  "sounds": [
    {
      "ipa": "/ˈɑːtuː/"
    },
    {
      "audio": "NB - Pronunciation of Norwegian Bokmål «A2».ogg",
      "mp3_url": "https://upload.wikimedia.org/wikipedia/commons/transcoded/0/01/NB_-_Pronunciation_of_Norwegian_Bokm%C3%A5l_%C2%ABA2%C2%BB.ogg/NB_-_Pronunciation_of_Norwegian_Bokm%C3%A5l_%C2%ABA2%C2%BB.ogg.mp3",
      "ogg_url": "https://upload.wikimedia.org/wikipedia/commons/0/01/NB_-_Pronunciation_of_Norwegian_Bokm%C3%A5l_%C2%ABA2%C2%BB.ogg"
    },
    {
      "rhymes": "-uː"
    }
  ],
  "word": "A2"
}