From USPTO.gov: “During the November 2007 Trilateral Conference, the United States Patent and Trademark Office (USPTO), the European Patent Office (EPO), and the Japan Patent Office (JPO) agreed on a common application format. This format, which was developed in consultation with users from the three regions, will simplify and streamline application filing requirements in each Office to allow applicants to prepare a single application in the common application format for acceptance in each of the three Offices.”
Basic Principles of the Common Application Format available here
Common Application Format available here.
Visit the Trilateral site for more information.