during the allied occupations of axis countries after world war ii, use and display of those nations' national flags was banned. in order to comply with the international legal requirement that a ship identify its registry by displaying the appropriate national ensign, swallow-tailed versions of the c, d, and e signal flags were designated as, respectively, provisional german, okinawan, and japanese civil ensigns. being swallowtails, they are commonly referred to as the "c-pennant" (german: c-doppelstander), "d-pennant", and "e-pennant".