法華玄義釋籤 1.105

1.105

既是不思議空假，還指空假即中，中為經體，中即空假亦指於中，三諦無非遍一切處。若得此意，《中論》四句義可準知。若四句對教自是別途，非此中意。

Since they are inconceivable emptiness and provisionality, they point back to emptiness and provisionality being identical to the middle. The middle is the essence of the sūtra, and the middle being identical to emptiness and provisionality also points to the middle. The three truths without exception pervade all places. If one grasps this meaning, the four propositions of the Mūlamadhyamakakārikā may be understood accordingly. If the four propositions are matched to the teachings, that is of course a separate path, not the intent here.