四分律刪繁補闕行事鈔 1.393

1.393

十三二形者。謂一報形，具男女二根。若先受後變，猶尚失戒；況初帶，受者，滅擯。

Thirteenth is an ubhatobyañjanaka. This refers to a single karmic retribution body possessing both male and female faculties. If one first received [the precepts] and then transformed, one still loses the precepts; how much more so if one possessed them at the outset—one who received them is expelled.