league match last week. northern california hard courts. three courts side by side. middle court has no chairs or bench. two end ones do as there is a side fence a bench can be placed against. so, i bring 2 plastic chairs - cheap white lightweight ones you can get at kmart - up to the middle court where my partner and i are playing. pro, in a nice and friendly manner, says no chairs can be placed on court because they'll leave a mark. i said fine. no confrontation. all is good. now, i've only played this here game for about 52 years. i've never had anyone say a plastic chair leaves a mark on a hard court. have you?