There is a suggestion from the referees of recent VRC events in Asia, which is the rope/string should be restricted no thinner than a given size in R7e, because there are many robots using very thin rope/string, which is hard to identify, and easy to move at the end of match. Following figures are examples of the case. At the end of the match, there are many thin strings all over the field, referee can hardly identify where they are, and when referee is trying to count the field tiles, a slight movement many change the status of the string (contacting the field or not), this makes referee crazy.
https://drive.google.com/file/d/17s_gdYEBEZHxq0me009fZSQwC0pEhPCW/view?usp=sharing
https://drive.google.com/file/d/1xDBB22Z_CpvANWTedh7I7s9rPrb6_YWU/view?usp=sharing