成唯識論了義燈 6.174

6.174

滅下四行空、無相攝。彼云：真如非三種，是空無相境，道四行相。若依能觀通三門攝，若約所觀空行所攝。彼云：正智通三種，是空所行境，准上所明，依相十六各三所攝，據餘四言，空攝十六，無願攝苦、集八，無相攝滅下四。又云：若無差別，總說為空、無願、無相，此與相同。准此中明，依相乃無差別，同第十二第三復次。

The four aspects under cessation are subsumed by emptiness and the signless. It says there: "Tathatā is not the three kinds; it is the object of emptiness and the signless." As for the four aspects of the path: if based on the observing [wisdom], they are subsumed by the three doors; if according to what is observed, they are subsumed by the practice of emptiness. It says there: "Correct knowledge extends to the three kinds, and is the domain of practice of emptiness." Following what is explained above, based on marks the sixteen are each subsumed by the three. According to the words of the other four [factors]: emptiness subsumes sixteen; the wishless subsumes the eight of suffering and arising; and the signless subsumes the four under cessation. It also says: "If without distinction, they are collectively stated as emptiness, wishlessness, and signlessness; this is the same as marks." Following what is explained here, based on marks there is indeed no distinction, identical to the third alternative of the twelfth fascicle.