The status of a permanent observer is based purely on practice of the General Assembly, and there are no provisions for it in the United Nations Charter.
The General Assembly may invite non-member entities to participate in the work of the United Nations without formal membership, and has done so on numerous occasions.
The Holy See did not wish to join the United Nations as a member because "Membership in the organization would not seem to be consonant with the provisions of Article 24 of the Lateran Treaty, particularly as regards spiritual status and participation in possible use of force.
[9] With the change in status, the United Nations Secretariat held that Palestine was entitled to become a party to treaties for which the UN Secretary-General is the depositary.
[10] On 17 December 2012, UN Chief of Protocol, Yeocheol Yoon, declared that "the designation of 'State of Palestine' shall be used by the Secretariat in all official United Nations documents.
[Note 1] Most of the former non-member observer states accepted this status at a time when they had applied for membership but were unable to attain it, due to the (actual or threatened) veto of one or more of the permanent members of the Security Council.
The vetoes were later overcome either by changes in geopolitical circumstances, or by "package deals" under which the Security Council approved multiple new member states at the same time, as was done with a dozen countries in 1955 and with East and West Germany in 1973.
Some of them maintain a permanent office in the United Nations headquarters in New York City, while others do not; however, this is the choice of the organization and does not imply differences in their status.
formerly the African, Caribbean and Pacific Group of States Some of UN Specialized agencies and related organizations are having permanent offices at the UN headquarters, some were auto-granted since their establishment (i.e. without passing General Assembly resolutions).