I was reminded of a couple of things while rereading a fly fishing book over the weekend.

1) The actual difference between one weight of flyline and the next is measured in hundredths of an ounce. Many of us aren't good enough casters to even notice the difference.

2) While line rating is a standard measurement using the actual weight of a measured portion of line, the weight rating of a fly rod is completely subjective and reflects the manufacturer/rod builders intent based on the way the rod was designed to be used. Unfortunately, there are few manufacturers that tell us under what conditions the rods was designed to be used. Why is that?