This button controls the backward movement of the play position pointer. Click SELECT on the Rev button to move the play position pointer backward.
If there is no selection in the canvas, clicking SELECT on the Rev button causes the pointer to jump backward, segment by segment, until it reaches the beginning of the file. (A segment is the start of a sound "box" in the display canvas.)
If there is a selection, the pointer's movement is constrained to the selection.
Hold down SELECT on the Rev button to play the selection in reverse at an accelerated speed until you release SELECT or until the play position pointer reaches the beginning of the selection.