How to use the country change feature?

I want to know more information about country change.

I would need to change my country after 1 year. But to change the country blizzard provides a country change feature which require a Government issued photo ID. So my question is this that it is also mentioned that we can send our most recent utility bill to change the country. So what do we need to send for government issued photo id? Photo of identity card or utility bill accepted?