成唯識論了義燈 6.179

6.179

今更略者，一說，准五十一，空攝二行，謂苦諦下空、無我行，無願攝六，謂苦諦下無常及苦并集下四，由觀苦果，因於三界中不願求故，無相攝四，即滅四行，道或通三，或非三攝。

Now to summarize further: One explanation, following [fascicle] fifty-one, says that emptiness subsumes two aspects, namely the aspects of emptiness and non-self under the truth of suffering; the wishless subsumes six, namely impermanence and suffering under the truth of suffering, together with the four under arising, because through contemplating the fruit and causes of suffering one does not wish or seek within the three realms; the signless subsumes four, namely the four aspects of cessation; the path either extends to all three, or is not subsumed by the three.