四分律刪繁補闕行事鈔 1.288

1.288

其內朱方，是戒場也。中間周匝，號曰自然。東北二邊，即用小牆下上為自然界體。南西二邊，大界牆內，則無別相者，應釘杙豎標，繩連相著。當於戒場東南角，去大界牆尺八地旁小牆施一杙。又於西南角斜去大牆二尺許下一杙。又於西北角至小牆南旁小牆下一杙，正西令去大牆尺八許。釘三杙已，仍以繩連三標，則為自然界。南西二邊，若作二法竟，若二界各有法事，此中有人，不妨二處。其戒場外相，東北二邊之相，即以小牆內院為相。西南二畔，即用繩標內邊為相。

The inner red square is the ordination platform. The surrounding space between is called 'natural'. For the northeast two sides, the top and bottom of the small wall are used as the substance of the natural boundary. On the south and west sides, inside the wall of the great boundary, where there are no other landmarks, pegs should be driven and markers erected, connected by a rope. At the southeast corner of the ordination platform, one foot and eight inches away from the wall of the great boundary, beside the small wall, place a peg. At the southwest corner, place a peg diagonally about two feet away from the great wall. At the northwest corner, place a peg south of the small wall and beside it, directly west and about one foot eight inches from the great wall. Having driven the three pegs, connect the three markers with a rope, which constitutes the natural boundary. On the south and west sides, once the two karmans have been completed, if the two boundaries each have ritual matters, having people within this [natural area] will not interfere with either place. As for the outer marks of the ordination platform, the marks for the northeast two sides use the inner compound of the small wall as the marks. The southwest two sides use the inner side of the rope markers as the marks.