Here’s a place to start. WIPO’s booklet: 20 Questions About the Madrid Protocol. For those of you who have fewer than 20 questions – the Madrid Protocol is an international treaty under which owners of a national trademark application or registration in its home country can ‘deposit’ that application or registration with WIPO in order to obtain an ‘international registration’ That regsitration can then be ‘extended’ to any other country that is a signatory to the Protocol. The point of all this is to streamline the process of filing and renewing trademark applications, and can result in significant savings. The U.S. has agreed to the treaty and starting November 2, you (you Americans that is) can begin filing those Madrid trademarks, and you (you non-Americans who live in the 57 other Protocol countries) can begin extending your International applications to the U.S.
Map of Madrid courtesy of and copyright Lonely Planet.