In “Nāgārjuna in Context” (New York, 2005) Joseph Walser attempts to give the monk-scholar Nāgārjuna a place in time and space. Whether he has been successful is not the subject of this short remark.
What is of interest here is the opinion among academics that there is something called Mahāyāna ordination and something called Hīnayāna ordination for Buddhist monks in the orthodox sense of the word.
Mr. Walser quotes Gregory Schopen with “…., for ordained Mahāyānists, ‘early Mahāyāna in India was a small isolated … group …”.
“Ordained Mahāyānists” needs to be clarified:
There are no Mahāyāna ordinations, and there have never been Mahāyāna ordinations. All orthodox Mahāyāna Schools employ, and employed, the Hīnayāna sets of rules. As such, or, as far as ordination goes, Hīnayāna is part of Mahāyāna.
As of unknown date Mahāyānists could and can enhance or “upgrade” their Hīnayāna ordination by taking on a number of Bodhisattva rules. Taking the Bodhisattva rules is optional. The ceremonies by which Bodhisattva rules are taken follow after the taking of Higher Ordination (upasampadá). Some of these rules repeat some rules of Lower Ordination (in the Hīnayāna sense of the word), some others are add-ons.
See also Buddhism, some aspects