What must a Referee check regarding a fencer's jacket and knickers?

The requirement for a fencer's jacket to overlap the knickers by at least 10 centimeters when in an on guard position is essential for safety regulations in fencing. This overlap helps ensure that there is adequate coverage to protect the fencer from potential injuries caused by the opponent's weapon. Proper attire coverage helps reduce the risk of cuts or punctures, which can happen if the uniform does not fit correctly or cover enough of the body.

The specific measurement of 10 centimeters is crucial because it provides a standardized guideline that can be easily assessed by the referee. This standard helps maintain uniformity in equipment checks, contributing to a fair and safe competitive environment. By adhering to this requirement, referees help enforce safety standards that protect the athletes while competing.