I think you also need to know that it sometimes is important to use the double bar at the end of a cell rather than the double bar at the beginning of the next cell, even though they look almost identical. For example, I have attached Bob's Every Time I Roll 2 here, but I changed the double bar in the cell with the first coda sign in it — i.e., the cell with the D.S. al Coda sign in it — by removing Bob's ending double-bar, going to the next cell and using a beginning double bar in that cell. Looks essentially the same, but it won't play correctly.

Every Time I Roll 2 - Max D. Barnes and Troy Seals