minecraft-bedrock-json-schemas/source/general/format_version.json

{
  "$id": "format_version",
  "title": "Format Version",
  "description": "A version that tells minecraft what type of data format can be expected when reading this file.",
  "pattern": "^(1)\\.([0-9]+)\\.([0-9]+)$",
  "type": "string"
}