I grew up playing on hard courts, but for the past year have been playing on the green Har-Tru courts. On the Har-Tru, about once every three sets, a serve will land and leave a four or five-inch skid mark right behind the service line (out). The receiver will call the ball out, but then walk up and examine the ball mark and see that there is no undisturbed clay between the service line and the ball mark (or that the ball actually caught the back 1/32 inch of the service line). In either situation, the receiver will then correct his call to "in" and the server will re-play the serve. Most people seem to have no problem with this protocol and most of the time the server is pleased that the opponent is honest enough to closely examine the mark to correct the call. However, this week one server in a doubles match became irate after this happened twice during one match. He said the receiver should never call the ball out unless he can instantaneously see that the ball clearly missed the service line. He said that even if the ball leaves a six inch skidmark behind the service line, the receiver should say nothing and should always play the ball unless the receiver can immediately see clear evidence that there is undisturbed clay between the back of the service line and the ball mark. I and others felt that that was demanding too much of the receiver, as you would have to concede not only the service line but the 6 to 8 inch area behind the service line. Most of us felt that the receiver should make his best good faith effort to call the ball as he saw it at the moment, always with the duty to correct a bad call. However, I did not grow up on clay, so I can't claim to be expert in the protocol. Help!