What is "moheyan"

Heshang Moheyan (和尚摩訶衍; Wade-Giles:Ho-shang Mo-ho-yen; Héshang Móhēyǎn or Hvashang Moheyan in Tibetan sources) was a late 8th century Chan monk associated with the Northern School. He became famous for representing Chán in the so called "Council of Lhasa," a debate between adherents of the Indian teachings of "gradual enlightenment" and the Chinese teachings of "sudden enlightenment," which according to tradition was won by the "gradual teachings."