The Compendium of Caraka 8.1.48

8.1.48

sānvāsanā dvādaśa vai nirūhāḥ prāk sneha ekaḥ parataśca pañca/
&kāle trayo 'ante puratastathaikaḥ snehā nirūhāntaritāśca ṣaṭ syuḥ//

Together with unctuous enemas, non-unctuous enemas are indeed twelve: first one unctuous enema, and five at the end;
in kālabasti there are three at the end and likewise one at the beginning, and there should be six unctuous enemas interposed with non-unctuous enemas.