An unextendable period is one kind of the statutory periods, and upon expiration of such period, forfeiture of light is to be effected unless a reinstatement is requested. As for the so-called “being deemed to be”, which means specific effect is to be initiated through a legal fiction that does not allow any party to submit any evidence to rebut against when specific requirement stipulated by laws is fulfilled. This is to be distinguished from “being presumed to be”, where certain effect is to be preliminarily initiated through a legal fiction but allow the party to submit evidence to rebut against when specific requirement stipulated by laws is fulfilled so as to mitigate the burden of proof. While Paragraph 2 of Article 30 of the Patent Act has stipulated that the period for submitting a certificate of deposit is within three months from the filing date, and further stipulated that the legal effect pertaining to an overdue submission is that such deposit is deemed to be never performed, this stipulated period is therefore a statutory unextendable period. As a result, unless Plaintiff has requested a reinstatement in accordance with Paragraph 1 of Article 50 of the Administrative Procedure Act or Paragraph 2 of Article 17 of the Patent Act, the overdue submission has triggered the legal effect of not-performed deposit.