When the term of office of the
Director-General
is due to expire. the appointment of a new Director-General shall be placed on the agenda of the regular session of the Conference immediately preceding the expiry of the term of office
; whenever,
for other reasons
, the office of the Director-General is vacant, or notice is received of a pending vacancy, the appointment of a new Director-General shall be placed on the agenda of the next session of the Conference which opens not less than 90 days from the occurrence or notice of the pending vacancy.