"NV1" meaning in Conventions internationales

{
  "categories": [
    {
      "kind": "other",
      "name": "Nomenclatures pigmentaires",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Symboles en conventions internationales",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Conventions internationales",
      "orig": "conventions internationales",
      "parents": [],
      "source": "w"
    }
  ],
  "etymology_texts": [
    "Par convention N pour les pigments d'origine naturelle. V pour violet (« mauve »)."
  ],
  "lang": "Conventions internationales",
  "lang_code": "conv",
  "pos": "symbol",
  "pos_title": "Symbole",
  "senses": [
    {
      "glosses": [
        "Pourpre de Tyr."
      ],
      "id": "fr-NV1-conv-symbol-A0UW9uRF"
    }
  ],
  "word": "NV1"
}

{
  "categories": [
    "Nomenclatures pigmentaires",
    "Symboles en conventions internationales",
    "conventions internationales"
  ],
  "etymology_texts": [
    "Par convention N pour les pigments d'origine naturelle. V pour violet (« mauve »)."
  ],
  "lang": "Conventions internationales",
  "lang_code": "conv",
  "pos": "symbol",
  "pos_title": "Symbole",
  "senses": [
    {
      "glosses": [
        "Pourpre de Tyr."
      ]
    }
  ],
  "word": "NV1"
}