minecraft-bedrock-json-schemas/source/general/entity/identifier.json

{
  "$id": "blockception.minecraft.entity.identifier",
  "description": "A minecraft entity identifier",
  "examples": ["namespace:entity_name"],
  "pattern": "^[0-9a-zA-Z:_\\.\\-]+$",
  "title": "Entity Identifier",
  "type": "string"
}