Swing is sometimes described as a groove, pulse, or feel, and I assume that there are as many words for comparable concepts as there are musical styles, languages, and cultures. On the syntactical level (that is, in the realm of crotchets and quavers and their subdivisions), jazz swing has never been effectively notated. Ridetaps, the drummer's tapping on a ride cymbal, are often represented by dotted rhythms or eighth note triplets, while a bass line is usually written as straight quarter notes. To these notated sketches, musicians add the "swing," making the notes come alive. What is it that they add? What is swing on the sub-syntactical level? Some may argue that swing results when musicians are playing precisely together, while others may insist that swing occurs when the musicians are a bit out of time, or out of phase with each other. Both musicians and analysts may disagree about these "together" and "apart" issues, so it is important for us to develop a systematic method, an etic grid, for measuring degrees of synchrony and discrepancy between musicians.