As an explicit rubric, this appears to be a Tibetan invention, c. 11th century. Above all, this refers to Candrakīrti, who also claimed Buddhapālita as his predecessor. One or two places in Candrakīrti's Prasannapadā seems to have references to Prāsaṅga possibly implying its use as a label. The Geluk later claim that this rubric also includes Maitreya-Asaṅga's Uttaratantra. Resources: * S. K. Hookham, The Buddha Within (Albany, NY: SUNY Press, 1991). This is an overview of the "emptiness of other" exegetical traditions in Tibet. * Jeffrey Hopkins, Meditation on Emptiness (London: Wisdom Publications, 1983). This is a detailed overview of "intrinsic emptiness" exegetical traditions in the Tibetan Geluk tradition.