The advent of vehicles, moving many times the velocity of sound makes it necessary to understand clearly the various phenomena occuring near the sharp leading edge of a flat plate. A few theoretical attempts to tackle this problem are made and several experiments are performed at various places. Unfortunately wide areas of disagree ment exist between the various theoretical investigations and experimental results. It is the purpose of the note to try to gather some useful information from the available literature on this subject and present some suggestions which might be useful or worth consideration in any future attempt of solving this problem. (Author).