List of possible regions for X-AppEngine-Region

Question

The GAE Docs on Request Headers say...

X-AppEngine-Region

Name of region from which the request originated. This value only makes sense in the context of the country in X-AppEngine-Country. For example, if the country is "US" and the region is "ca", that "ca" means "California", not Canada.

Where can I get a list of all regions that could be returned? And why does it have to return "ca" when it can just return "California"?

Thanks!

Answer 1

The complete list is in ISO-3166-2 standard.
That's why it return "ca" and not 'California": this is a standard like country codes.