The school or principle of the mean, represented by the 法相宗 Dharmalaksana school, which divides the Buddha's teaching into three periods, the first in which he preached 有 existence, the second 空 non-existence, the third 中 neither, something 'between' or above them, e. g. a realm of pure spirit, vide the 深密經 Saṃdhinirmocana-sūtra and the Lotus Sutra.

A Dictionary of Chinese Buddhist Terms, William Edward Soothill and Lewis Hodous

（流派）中道之宗旨也。法相宗立三時教，以第三時教，為自家之非有非空之中道教。即法相宗也。唯識樞要上本曰：「中宗五分，盛行於四主。」

丁福保《佛學大辭典》