WIPO Regulations for International Patent Applications under the PCT

Rule 7

The Drawings
7.1       Flow Sheets and Diagrams
Flow sheets and diagrams are considered drawings.
7.2       Time Limit
The time limit referred to in Article 7(2)(ii) shall be reasonable under the circumstances of the case and shall, in no case, be shorter than two months from the date of the written invitation requiring the filing of drawings or additional drawings under the said provision.