So salmon rods, spinning rods and beach casting rods show a recommended weight and you say that fly rods are not a special case yet they don't need to show a recommended weight? I think you're just being stubborn now.
If fly lines stuck to their standard and if fly rods had not developed beyond their original purpose, the AFTTA code would be fine, but they don't and they haven't. So, just like the salmon line rating and rod weightings changed, fly rods need to change too.
Such a lot of waffle from you on this; so was just wondering if you realise that you are free to put whatever numbers and any other nonsense on your rods that suits you?
I imagine it would be especially helpful if when you put a line on and you can’t actually tell if it is to your liking or not, without a corresponding array of numerical classification digits that perfectly align to determine “it’s the one”…
The good news is, that you really don’t have to ask for permission, and it really doesn’t matter if nobody else agrees with what you write on them.. …and also that, at the end of the day if you really can’t get it to work for you, if all else fails - and your rod is a #5wt., you could always try a #5 line?