Subscription list for public issues shall be kept open for at least 3 working days and not more than 10 working days. In case of Book built issues, the minimum and maximum period for which bidding will be open is 3 � 7 working days extendable by 3 days in case of a revision in the price band. The public issue made by an infrastructure company, may be kept open for a maximum period of 21 working days. Rights issues shall be kept open for at least 30 days and not more than 60 days.