大乘義章 1.91

1.91

理體名法，又為心軌，亦名為法。此不二法，形對佛性空如等義，門別不同，故名為門。又能通人，趣入名門。捨相證會，名之為入。名義如是。

The essence of principle is called dharma; moreover, being a standard for the mind, it is also called dharma. This non-dual dharma, in contrast to the meanings of Buddha-nature, emptiness, suchness, and so forth, has distinct gates, and is therefore called a gate. Furthermore, being able to provide passage for people, going forward into it is called a gate. Relinquishing characteristics and verifying realization is called entering. Such is the meaning of the name.