In the case of regional organisations, such as the Council of Europe or the Organization of American States, the set of negotiating states that once agreed upon may sign and ratify the treaty is usually limited to its own member states, and non-member states may accede to it later. However, sometimes a specific set of non-member states or non-state actors may be invited to join negotiations. For example, the Council of Europe invited the "non-member States" Canada, the Holy See (Vatican City), Japan, Mexico and the United States to "participate in the elaboration" of the 2011 Istanbul Convention and specifically allowed the European Union (described as an "International Organisation," rather than a "State") to sign and ratify the convention, rather than accede to it, and "other non-member States" were allowed only accession.