大方廣圓覺修多羅了義經略疏 2.111

2.111

Originally, based on producing the mind [for bodhi] and cultivating realization, the five natures are established in terms of severing the two hindrances; since these are not severed at all, they do not count among the five, nor have they produced the mind and encountered the teachings, hence they are said to be 'not yet perfumed.' According to the text of the Laṅkāvatāra, this corresponds to the fifth, the natureless.