"XIST" meaning in Conventions internationales

{
  "categories": [
    {
      "kind": "other",
      "name": "Noms scientifiques",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Conventions internationales",
      "orig": "conventions internationales",
      "parents": [],
      "source": "w"
    }
  ],
  "etymology_texts": [
    "(Vers 1990) Initiales de l'anglais X inactive specific transcript."
  ],
  "lang": "Conventions internationales",
  "lang_code": "conv",
  "pos": "noun",
  "pos_title": "Nom scientifique",
  "senses": [
    {
      "glosses": [
        "Variante de Xist."
      ],
      "id": "fr-XIST-conv-noun-S7ljSznY"
    }
  ],
  "word": "XIST"
}

{
  "categories": [
    "Noms scientifiques",
    "conventions internationales"
  ],
  "etymology_texts": [
    "(Vers 1990) Initiales de l'anglais X inactive specific transcript."
  ],
  "lang": "Conventions internationales",
  "lang_code": "conv",
  "pos": "noun",
  "pos_title": "Nom scientifique",
  "senses": [
    {
      "glosses": [
        "Variante de Xist."
      ]
    }
  ],
  "word": "XIST"
}