四分律刪繁補闕行事鈔 1.268

1.268

問：界得重結不？答：律云，不得二界相接，應留中間。若疑有者，解已更結。故不開重。

Question: May a sīmā be demarcated repeatedly over another? Answer: The Vinaya says that two sīmās must not abut each other; an interval should be left between them. If one suspects that one exists, disband it and then demarcate again. Therefore overlapping demarcation is not permitted.