俱舍論頌疏論本 1.126

1.126

如是受等三，及無表無為，名法處法界者，立處、界門。受等三者，等取想、行，名三也，并無表成四，及三種無為成七。此等七法，十二處中名為法處，十八界中名為法界。

"These three, sensation and the rest, as well as the non-informative and the unconditioned, are called the dharma base and dharma element" establishes the category of bases and elements. "These three, sensation and the rest" takes conception and formations as the rest to make three; combined with the non-informative they make four; and with the three kinds of unconditioned dharmas they make seven. These seven dharmas are called the dharma base among the twelve bases, and are called the dharma element among the eighteen elements.