I. The ten functions in the Traces are summarized by Chih-i specifically and generally. Summarizing specifically the ten functions with the Four Siddhāntas shows that the ten functions can be divided into four groups and each of these four groups of function corresponds to each of the Four Siddhāntas. …

In terms of the functions that can be summarized by the Worldly Siddhānta, “abiding in the three and revealing the one,” and “abiding in the one and employing the three” are said by Chih-i to correspond with the Worldly Siddhānta. This is because by abiding at the Three Vehicles and by employing the Three Vehicles, the Buddha caters to the intellectual capabilities of living beings. Complying with the needs of beings in teaching various vehicles belongs the Worldly Siddhānta. (Vol. 2, Page 449)