It is important to manage your fly line when casting especially in windy conditions. Stepping on the line or pulling on the line to remove it from sticking points can crease or cut the coating on the line. Pay particular attention to not crimping your line when changing spools. The line can become momentarily wedged between the spool and the reel frame and damage the coating. Closing the line in a sharp edged fly box happens to me. I have had an amazing Kamloops torpedo stip our line so fast and once the line went taught the intermediate line snapped and stripped up through the guides in a heart beat. There went the fish and there went half my fly line. I had at some point cut deeply into the coating and apparently the core. Now in the above situation, I think the angler is assured of no damage to the line.    

Photo by Denver Bryan (Images on the Wildside)