瑜伽論記 4.252

4.252

即於欲界諸色，以有光明相作意思惟等者，此明觀義，不同小宗作不淨想，今此說觀光明想故，有二因緣名為有色：一、生欲界得色界定故；二、於光明而作勝解故。

The statement "namely, with respect to forms of the desire realm, mentally reflecting on them with the mark of light, etc." clarifies the meaning of contemplation. Unlike the Hīnayāna school's cultivation of the notion of impurity, here it speaks of contemplating the notion of light. There are two conditions for being called "having form": first, being born in the desire realm and attaining the form-realm concentration; second, producing resolute conviction regarding light.