From the date on which a third party provides evidence that he has instituted national proceedings under Rule 14, paragraph 1, and up to the date on which the proceedings for grant are resumed, neither the European patent application nor the designation of any Contracting State may be withdrawn.
Source: http://www.epo.org/law-practice/legal-texts/html/epc/2016/e/r15.html
Date retrieved: 17 May 2021