def pageId(self, pageId):
        """
        Set the ID of the physical page this file manifests.
        """
        if pageId is None:
            return
        if self.mets is None:
            raise Exception("OcrdFile %s has no member 'mets' pointing to parent OcrdMets" % self)
        self.mets.set_physical_page_for_file(pageId, self)