四分比丘戒本疏 2.75

2.75

第四十五戒與女露坐者，准律釋相中云屏處者，見屏處、聞屏處也，以無屋覆名之為露。又離見聞復稱為屏，離見聞屏尚自是犯，覆障之處理應亦犯，即是義含覆屏也。此戒無夫，不簡道俗女犯也。若有第三人，不犯也。

The forty-fifth precept, sitting in the open with a woman: According to the explanation of characteristics in the Vinaya, it states that a screened place means a place screened from sight and a place screened from hearing; being without a roof covering is termed 'in the open'. Furthermore, being removed from sight and hearing is also called 'screened'; since being in a place screened from sight and hearing is already an offence, being in a covered, obstructed place ought by principle to also be an offence, meaning that the sense implicitly includes covered and screened [places]. In this precept there is no husband, and it makes no distinction between ordained and lay women for an offence to occur. If there is a third person, he commits no offence.