四分律行事鈔資持記 2.32

2.32

答文，《了論》中，初約喻以顯。四處，即腦咽心腰。由下，示不階之意。即《雜心》云：非第一義比丘是也。

In the text of the answer, in the Vinayadvāviṃśatividyā-śāstra, it first makes it clear through a simile. The four places are the brain, throat, heart, and waist. Following "Due to," it indicates the meaning of not ascending [the stages]—namely, what the Za xin calls: "He is not a bhikṣu in the ultimate sense."