Google sheet embed URL documentation

Does anyone know if there is any official documentation for google spreadsheet embed URL paramaters?

That is, given an embed URL from Google Sheets like this:
https://docs.google.com/a/aicr.org/…

JSON import to Excel

Is it possible to script JSON calls in a macro?

I want to get a JSON string through an API connection. It looks like the problem is Excel expects the parameters to be passed in the HTML-string, but …