俱舍論頌疏論本 2.32

2.32

餘九色所造者，餘謂所餘眼等五根、色等四境，唯除觸也，此九色界唯所造性。法一分亦然者，法界一分無表業色，同前九界，亦唯所造，故言亦然。法界中有四分法：一相應法、二不相應法、三無表色、四無為法。今唯取無表，故言一分也。

Regarding "the other nine rūpas are derived matter": "the other" refers to the remaining five faculties of the eye and so forth, and the four objects of visible form and so forth, excluding only tangibles; these nine rūpa-dhātus are exclusively of the nature of derived matter. Regarding "a part of dharma is also like this": avijñapti-karma-rūpa, which is one part of the dharmadhātu, is the same as the previous nine dhātus in being exclusively derived matter; hence it says "is also like this". In the dharmadhātu there are four parts of phenomena: 1. associated phenomena, 2. unassociated phenomena, 3. avijñapti-rūpa, and 4. unconditioned phenomena. Here, taking only avijñapti, it says "one part".