An example of creation of a document with Centrifuge API

Im following the Node API documentation. When I click on Try it out button, I got the following:

  "attributes": {},
  "data": {},
  "document_id": "string (optional)",
  "read_access": [
  "scheme": "string (optional)",
  "write_access": [

What can I put on string (optional) in both places. There is some example of a creation document around there?
I’m using a centrifuge node connected to flint testnet, and I’m doing http request using postman.