What is the maximum period upto which a proclamation issued by the President under Article-356 of the Constitution and approved/extended by the Parliament may, normally, remain in force?

State Emergency declared under the provision of Article-356 by President must be approved by Parliament within two months. After approval by parliament, it may remain in operation for not more than 6 months from the date of proclamation unless after 6 months parliament extends it. Parliament can extend it by approval after every six months. It can be withdrawn anytime by President.