大乘百法明門論疏 2.30

2.30

此則第三、明色法，就中有二：初、牒章，第二、舉數列名。言第三色法者，此則第一牒章。言色者，質礙之法名之為色。

This is the third [part], explaining rūpa-dharmas. Within this there are two: first, stating the heading; second, giving the number and enumerating the names. Regarding "Third, rūpa-dharmas": this is the first [part], stating the heading. Regarding "rūpa" (matter/form): dharmas of spatial resistance are named rūpa.