How do ball mark inspections work on clay?

Under the Ball Mark Inspection Procedures in the Rules of the Court:

1. Ball mark inspections can only be made on clay courts.
2. A player-requested inspection is allowed only if the chair umpire cannot determine the call with certainty from the chair, on either a point-ending shot or when the player stops playing the point during a rally (returns are permitted but then the player must immediately stop).
3. When the chair umpire decides to inspect, they go down from the chair and inspect the mark themselves. If they do not know where the mark is, they can ask the line umpire to help locate it, but the chair umpire shall inspect it.
4. The original call or overrule stands if the line umpire and chair umpire cannot find the mark or it is unreadable.
5. Once the chair umpire has identified and ruled on a mark, the decision is final and not appealable.
6. On clay the chair umpire should not be too quick to announce the score unless absolutely certain of the call; if in doubt, wait to see whether an inspection is needed.
7. In doubles the appeal must stop play or the chair umpire must stop it; if the procedure was wrong or late, the chair umpire may determine the opponents were deliberately hindered.
8. A player who erases the mark before the chair umpire's final decision concedes the call.
9. A player may not cross the net to check a mark (Unsportsmanlike provision of the Code of Conduct). In a match with no chair umpire on clay, a player can ask the opponent to show the mark and then cross to check it.