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. The act of signing and ratifying a treaty as a negotiating state has the same effect as the act of acceding to a treaty (or "acceding a treaty") by a state that was not involved in its negotiation. Usually, accessions occur only after the treaty has entered into force, but the UN Secretary General has occasionally accepted accessions even before a treaty went into force. The only downside of not being a negotiating state is that one has no influence over the contents of a treaty, but one is still allowed to declare reservations with respect to specific provisions of the treaty that one wishes to accede to (Article 19). Statehood question When a treaty is open to "States", it may be difficult or impossible for the depositary authority to determine which entities are States. If the treaty is restricted to Members of the United Nations or Parties to the Statute of the International Court of Justice, there is no ambiguity. However, a difficulty has occurred as to possible participation in treaties when entities that appeared otherwise to be States could not be admitted to the United Nations or become Parties to the Statute of the International Court of Justice because of the opposition for political reasons of a permanent member of the Security Council or have not applied for ICJ or UN membership. Since that difficulty did not arise as concerns membership in the specialized agencies, on which there is no "veto" procedure, a number of those States became members of specialized agencies and so were in essence recognized as States by the international community. Accordingly, to allow for as wide a participation as possible, a number of conventions then provided that they were also open for participation to States members of specialized agencies. The type of entry-into-force clause used in the Vienna Convention on the Law of Treaties was later called the "Vienna formula," and its wording was used