Article 60

(1) This Treaty may be revised from time to time by a special conference Of the Contracting States.

(2) The convocation of any revision conference shall be decided by the Assembly.

(3) Any intergovernmental organization appointed as International Searching or Preliminary Examining Authority shall be admitted as observer to any revision conference.

(4) Articles 53(5), (9) and (11), 54, 55(4) to (8), 56, and 57, may be amended either by a revision conference or according to the provisions of Article 61.