Csound1 wrote:
iCal is an app, not a standard, and it has been replaced by Calendar, the format they both use is .ics.
Oh, I'm so sorry to have to embarrass you in public like this, but you should know a little more about what you're talking about before posting on the Internet.
iCal is indeed a standard. It just happens to be named after the first program to implement that standard, Apple's iCal. See IETF RFC 2445 and 5545. These are real, open standards, by a standards body — the Internet Engineering Task Force — not just "industry standards", like Google or Exchange or Outlook. This is why so many mail clients and servers use iCal for data exchange, especially now on top of CalDAV (another open, not industry, standard.)
To use Google as a client for iCloud calendars you need this: iCloud Calendar Proxy,
This is the type of proxy I referenced in my previous post. You can use a service like this, or run your own. Thank you for sharing your search-foo.