פירוש על קידושין 103:3

The Tavyumi source clearly holds that kiddushin that cannot be followed by betrothal are kiddushin. Rava’s statement is refuted and the halakhah follows Abaye. The Talmud ends by noting that the halakhah follows Abaye in six cases which can be remembered by the acronym, Y’Al KGM. The K stands for kiddushin that cannot be followed by betrothal.