Target a page post by countries, cities, regions or language

As a user who publishes a post on a page wall I want to target the post by location and/or language.

Facebook has a special optional parameter for this:

Parameter name: targeting
Description: JSON object containing countries, cities, regions or locales
Type: string containing JSON object
Example:

{'countries':['US','GB']}

http://developers.facebook.com/docs/reference/api/page/

I haven't been able to find a better documentation about the acceptaed values.

When retrieving a post, the target values schould be displayed in the privacy value:
"The description field may contain a comma-separated lists of valid country, city and language if a Page's post targeting by location/language is specified."
http://developers.facebook.com/docs/reference/api/post/