Full-time members of the staff, with the exception of those specifically excluded by resolution of the General Assembly, shall be entitled to a children's allowance of $US 200 per annum in respect of each child under the age of eighteen years, or, if the child is in full-time attendance at a school or a university (or similar educational institution), or is totally disabled under the age of twenty-one years; provided that, if both parents are members of the staff of the United Nations, only one allowance will be paid in respect of each of their children; and provided further that, where the Secretary-General deems it advisable, no allowance or an allowance of an amount other than $US 200 may be paid under special circumstances, as for uample, short-term assignments or assignments at duty stations where the levels of United Nations salary scales are fixed at levels varying from the Headquarters scale.