For the United States: You may specify different states by using the 2-letter codes of states. Make sure to separate states with (,) comma.  

For all countries other than the United States: You may specify multiple countries (as may be needed in Europe for example) by using the entire country names separated by comma (,)   Write each country name entirely - do not use shorthand codes for countries (e.g. write GREECE instead of GR and ITALY instead of IT).

Currently, no subdivisions are used below the level of a country name (except from the United States), because the membership can still fit in one screen. If the membership from a particular country exceeds certain numbers that make display too large, we will then introduce subdivisions such as states/provinces/parishes as needed. Until such time however, you may specify entire countries (outside the United States).