铅笔画不出的界线橡皮擦不掉的距离
[qiān bĭ huà bù chū de jiè xiàn xiàng pí cā bù diào de jù lí]
Using metaphors of a pencil and an eraser, this name conveys undefined boundaries or unerasable distances, suggesting things that cannot be changed or removed easily, either tangible or intangible.