minecraft-assets/data/minecraft/chat_type/chat.json

{
  "chat": {
    "parameters": [
      "sender",
      "content"
    ],
    "translation_key": "chat.type.text"
  },
  "narration": {
    "parameters": [
      "sender",
      "content"
    ],
    "translation_key": "chat.type.text.narrate"
  }
}