成唯識論演祕 7.571

7.571

謂異熟等四，加自性一。自性體者，謂諸色根是長養者，及外諸有色處等。非異熟等所攝者，除善，染污色處、聲處。

This refers to the four such as ripening, with the addition of one by own-nature. As for the substance of own-nature, it refers to the material sense faculties that are nourished, as well as external material sense bases and so forth. Those not included in ripening and the others exclude good and defiled material sense bases and sound bases.