四分律刪繁補闕行事鈔 1.275

1.275

先須東南角為始，周匝直指相當。律云：東方有山等。若依東方而唱，至角曲迴，則不分限齊。今行事者，據易為之。

One must first take the southeast corner as the start, pointing straight to the corresponding points in a full circuit. The Vinaya says: 'In the eastern direction there is a mountain,' and so on. If one chants based on the eastern direction, when reaching the corners and turning, the limits and boundaries will not be aligned. Practitioners today proceed according to what is easiest.