金光明經文句記 2.187

2.187

三、「經家」下，明從圓題品。題稱壽量，正在報身，此從信相圓解所見。蔽，猶當也。舉報身一，當三身諸也。

Third, from "The compiler of the sūtra..." onward, it explains entitling the chapter according to the perfect. The title's stating "span of life" refers precisely to the reward body; this is seen from Ruciraketu's perfect understanding. Bi (to cover) is like dang (to match/equal). Adducing the single reward body equals all the various three bodies.