It appears that it's possible to get an extension for a P-3 visa, in one-year increments. Does the extension apply to the expiration date, or to the limit for the stay in the US?
If the expiration date can be extended, what form do I use to apply for the extension? I've tried asking the government, but the reply to my email from USVisa@state.gov essentially says "sorry, we can't answer your question".