In accordance with the invention, {HEAD ~ a timing signal} is recorded containing certain information that is used, upon playback, to produce a reference marker which is compared with the detectable characteristics of recorded information signals to produce a measure of {TAIL ~ skew distortion} 
In accordance with the invention , { HEAD ~ a timing signal } is recorded containing certain information that is used , upon playback , to produce a reference marker which is compared with the detectable characteristics of recorded information signals to produce a measure of { TAIL ~ skew distortion }
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL