Each unit is to be imagined as a flat rigid rod/hoop/triangle/etc.
https://en.wikipedia.org/wiki/Borromean_rings
Similar to BP252.
Adjacent-numbered pages: BP1128 BP1129 BP1130 BP1131 BP1132  *  BP1134 BP1135 BP1136 BP1137 BP1138
precise
Leo Crabbe
Put differently, if the examples are imagined to be arrangements of rigid sticks/hoops/etc resting on a flat surface, positive examples include sticks/hoops/etc that could be picked up without disturbing the other objects.
Adjacent-numbered pages: BP1130 BP1131 BP1132 BP1133 BP1134  *  BP1136 BP1137 BP1138 BP1139 BP1140