FWIW, if you are in the position of only being able to get a Clarks cable, they stamp the ends with (what you would assume) is the end that you need for a particular fitting (a C and a S, respectively). HOWEVER, I have learnt from experience that what they actually mean is that you chop off that end for that particular use (so counter-intuitive).
Doesn't say anything about it on the packet, and fortunately I was able to compare and contrast the ends in the comfort of my garage, not out on the road.